Results
#1. MSA given as 12,000ft, flying over mountains in temperatures +9°C, QNH set as 1023 (obtained from a nearby airfield). What will the true altitude be when 12,000ft is reached?
- TRUE ALTITUDE = ALTITUDE ON QNH (ISA DEVIATION x 4 x PRESSURE ALTITUDE ÷ 1000)
Alt on QNH = 12000ft
Isa deviation = 18 ( supposed to be -9 but it is 9)
Ta =[12000 + ( 18x4x12000) ] /1000
Ta = 12864
#2. The lowest temperature in the international standard atmosphere (ISA) is?
The ICAO ISA is defined as follows:-
a MSL temperature of 15°C
a lapse rate of 0.65°C/100m (1.98° C /1000 ft) up to 11 km (36,090 ft)
a constant temperature of –56.5°C from 11 km (36,090ft) to 20 km (65,617 ft)
after which the temp increases with height ( inversion).
hence lowest is -56.5°C
CONVERT THE ANSWER IN KELVIN
273 (-56.5) = 216.5°K
#3. Why do TRS not occur in the SE Pacific and South Atlantic?
#4. Which frontal or occlusion system is the fastest moving?
#5. In the Northern Hemisphere a man observes a low pressure system passing him to the south, from west to east. What wind will he experience?
#6. From the pre-flight briefing you know a jet stream is at 31000 ft whilst you are at FL270. You experience moderate C.A.T, what would be the best course of action?
#7. When would a rotor cloud be ahead of a Cb?
Above picture shows mature stage
roll cloud are also rotor clouds
#8. On a significant weather chart you notice a symbol with the letter “H” and the number “400” inside. What does this imply?
#9. What are the conditions under which advection fog will be formed?
#10. You are at 12,000 ft (FL120) with an outside air temperature is -2°C. Where would you find the freezing level?
#11. What cloud does hail fall from?
#12. How does a polar front depression normally move?
#13. What is a cold pool, in the northern hemisphere?
These are outbreaks of cold air from near the poles. These outbreaks are usually characterized by a cold front at their leading edge. In fact they are common just behind the polar front depressions behind the cold front itself. Typically the air is unstable and therefore expect cumuliform activity with showers and even thunderstorms.
#14. Flying away from a low pressure at low levels in the Southern Hemisphere, where is the wind coming from?
#15. What is Relative Humidity dependent upon?
Relative Humidity is a term used to describe the quantity of water vapour that exists in a gaseous mixture of air and water. Relative humidity is expressed as a percentage and is calculated using the formula below. More simply, the relative humidity is the amount of water vapour present in a volume of air divided by the maximum amount of water vapour which that volume could hold at that temperature expressed as a percentage.
#16. The ITCZ in July is?
#17. If the ELR is 0.65°C/100m
#18. Using the diagram shown, what cross section is through an occluded front?
#19. Where are you most likely to find moderate to severe icing?
Rain ice occurs in a narrow range of altitudes at low level, about 1000 ft, ahead of a warm front or occlusion and is associated particularly with the moderate continuous rain which often falls from Nimbo Stratus cloud
#20. What is true about the dew point temperature?
#21. Height of the tropopause at 50° N
#22. What kind of weather system might you typically find between the 45° – 70°N?
#23. What are the indications of a TRS from a great distance?
#24. What is true regarding super cooled water droplets?
#25. Flying from London to Bombay in January, what average wind might you expect?
The direction of jet streams is generally westerly, maximum speeds occur near the tropopause, 200 kts have been recorded in Europe/N Atlantic and 300 kts in Asia.
hence westerly would be prominent
we will not encounter polar jet stream as we are not going towards the pole
#26. What is most different about the Equatorial Easterly jet stream?
#27. What pressure systems affect the North Atlantic in summer?
North American or Canadian Low replaces Winter High. Icelandic “Statistical” Low 1010 mbs. Less deep and split. Azores High 1025 hPa intensified. Further North at 35°N. Hurricanes in Caribbean and Florida area.
#28. Flying towards a warm front, at what distances might you expect the following cloud types from the surface position of the front?
#29. A characteristic of a stable air mass
#30. Wind is caused by?
#31. How do you recognise high level jet streams and associated CAT?
From the ground, when the cloud amounts allow, jets may be recognised by wind blown wisps of CIRRUS cloud blowing at right angles to the clouds at lower levels.
#32. What weather might you expect behind a fast moving cold front?
#33. Which conditions lead to mountain waves?
#34. How would an unstable atmosphere likely reduce the visibility?
#35. Where is the coldest air in a cold occlusion?
#36. Which is true regarding a polar front jet stream?
#37. What causes low level cloud in front of the warm front?
.
#38. Which of the following indicates upper level instability and possible the formation of TS?
#39. Where is the largest chance of squalls occurring?
Squall line with embedded bowing line segments often located along or north of warm front southward across warm sector along or ahead of cold front.
#40. When are the north Atlantic lows at their most southerly position?
#41. ELR is 1ºC/100m
The ELR now matches the DALR meaning that dry parcels will be neutral. And no vertical movement
DALR = ELR > SALR.
#42. A layer of air cooling at the SALR compared to the DALR would give what kind of cloud?
#43. Typical tornado diameter
tornadoes 100m to 150 m
#44. For the same pressure gradient at 50N, 60N and 40N, the geostrophic wind speed is?
#45. In the area of the ITCZ why are the heights of the tropopause not reported?
the trade-winds converge and air rises high into the upper reaches of the “troposphere.”
The strong updraft in the ITCZ raises the tropopause, the upper boundary of the troposphere, to about 15 km height
#46. What is a SPECI?
#47. Flying condition in Ci cloud and horizontal visibility
#48. A parcel of air cooling by more than 1°C/100m is said to be?
#49. Description of radiation fog
#50. The wind in the Northern Hemisphere at the surface and above the friction layer at 2000 ft would be?
#51. Flying over an airfield, at the surface the temp is -5ºC, freezing level is at 3000ft, rain is falling from clouds with a base of 4000ft caused by warm air rising above cold air. When would you experience icing?
met reports inversion warm air rising ( increase in temp with height)
-5° at ground then 0° level will be just above
hence
Yes, between ground level and 3000 FT/AGL
#52. Where are easterly and westerly jets found?
#53. Climbing out of Dhahran, Saudi Arabia on a clear night you suddenly lose your rate of climb. Why?
Vertical windshear is change in wind velocity with height. It is typically measured in knots per 100ft. This type of windshear is very common during an inversion, therefore expect them at night and in well developed high pressure systems such as those found under the sub tropical high pressure belt. As an aeroplane fly’s through an inversion, not only will the change of temperature cause the engine performance to change, but the abrupt change in wind speed and direction may significantly alter the flight path.
#55. What is the composition of Ci cloud?
#56. At 15,000ft in nimbostratus cloud with an outside air temperature of -12°C, what icing might you expect?
#57. What cloud types are classified as medium cloud?
#58. Comparing rain to drizzle, visibility will generally…?
#59. What is the approximate height of the tropopause at 50ºN?
#60. What statement is true regarding the tropopause?
#61. Isolated TS occur mostly due to
Heat, or airmass type (more common in summer time).
Also called isolated
are formed by thermal triggering or CONVECTION
not by frontal uplift
#62. Please refer to Appendix F (attached on the next page) What is the temperature deviation, in degrees Celsius, from the International Standard Atmosphere overhead Frankfurt (50N 08E) at FL 180 ?
#63. What type of cloud is associated with drizzle?
Stratus (from Latin stratum, meaning strewn) is generally a grey, layered cloud with a fairly uniform base, which may produce drizzle, or light snow. Stratus cloud is no more than 1,000 – 1 500 ft thick, and is often much thinner. Stratus is usually the lowest of all cloud types.
#64. Polar front depression normally move
#65. Fair weather cumulus gives an indication of
#66. QNH in a METAR is
#67. What cloud type are you least likely to get icing from?
#68. Thermal lows usually develop
#69. When flying from South to North in the Southern Hemisphere crossing over and above a polar frontal jet at FL 400, what might happen to the OAT?
PFJ ARE LOCATED IN WARM AIR
#70. TAF’s are usually valid for
#71. What type of jet stream blows constantly through the northern hemisphere?
Sub tropical jetsteams form in the area of the sub-tropical anti-cyclones. They are more or less permanent but move seasonally with the sub-tropical highs. They occur in the latitude bands 25° to 40° in winter and 40° to 45° in summer. The jet core is at the 200 hPa level.
#72. Tornadoes are usually associated with which cloud type
#73. Why is clear ice such a problem?
can be very dangerous. There can be much flowback and the ice appears transparent because there is no air trapped under the flowback icing. The lamination of the ice into layers increases its strength and because it has less air in it this type of ice is much stronger and much harder to remove.
The ice will destroy aerofoil shapes and its weight can cause problems of control because the build-up can be uneven.
Propeller icing can cause severe vibrations and as the ice adheres strongly, when it breaks off, the pieces can be large and cause skin damage.
#74. Wind at altitude is usually given as …….. in ……..
#75. What best shows Altocumulus Lenticularis?
Altocumulus lenticularis, also known as lenticular cloud, is found downwind of mountainous or hilly areas, and is indicative of the presence of mountain wave activity. Because of its position downwind of high ground, moderate or even severe turbulence may be found beneath altocumulus lenticularis.
#76. The surface wind circulation found between the sub tropical highs and the equatorial lows are called?
#77. A steep pressure gradient is characterised by
Closely spaced isobars imply a steep pressure gradient (common in low pressure systems) and widely spaced isobars imply a shallow pressure gradient (common in high pressure systems).
#78. An occlusion is mimicking a cold front, where would the coldest air be found?
#79. Assuming a generalised zonal distribution of winds, which zones on the diagram contain the temperate lows?0
#80. In a high pressure systems
#81. If you fly with left drift in the Northern Hemisphere, what is happening to your true altitude?
Buys Ballot’s Law states that: If an observer stands with his back to the wind, the lower pressure is on his left in the northern hemisphere, and on his right in the southern hemisphere.
A corollary of this law is that if an aircraft is experiencing starboard drift in the northern hemisphere the aircraft is heading towards low pressure
in this case the drift is to the left ( port) hence heading towards high pressures
True altitude in High pressure or warm atmosphere is always more than cold/low ,
#82. Over flat dry land what would cause cloud?
#83. What type of icing requires immediate diversion?
#84. Where does freezing rain come from?
#86. Without the ability to de-ice or land immediately, what should you do if you encounter rain ice at about 2,000ft?
#87. Flying from Dakar to Rio de Janeiro, where is the ITCZ in winter?
#88. What is the feature W?
#89. At a stationary front
stationary front is a weather front or transition zone between two air masses (cold and warm), when neither air mass is advancing into the other at a speed exceeding 5 knots at the ground surface.
#90. Using the picture shown above, what will be expected to happen to the surface pressure after the feature Y has passed?
#91. In central Europe, where are the greatest wind speeds?
Jet streams ,The direction of jet streams is generally westerly, maximum speeds occur near the tropopause, 200 kts have been recorded in Europe
#92. A man is flying East to West in the Northern Hemisphere. What is happening to his altitude?
#93. Sublimation is
Freezing
If the water droplet is cooled below zero, then it may change state again to ice.
Melting
The opposite change of state, from solid to liquid, is called melting
Sublimation/Deposition
Sublimation is the change of state directly from water vapour to ice without water droplets being formed. Latent heat is released. This process is also known as deposition.
The change of state from ice directly to water vapour is also called sublimation.
#94. Up to FL180 ISA Deviation is ISA -10°C. What is the actual depth of the layer between FL60 and FL120?
#95. Standing in the Northern Hemisphere, north of a polar frontal depression travelling west to east, the wind will
#96. In central Europe in summer, under the influence of a polar depression in a wide warm sector, you would expect the following wx:
#97. What is the coldest time of the day?
As per diurnal variation of temperature
From 15:00 LMT onwards, the temperature falls continuously until a little after sunrise. The lowest temperature occurs at about sunrise plus 30 minutes. (TMIN)
#98. An Easterly wave will produce:
#99. Which of the following would lead to the formation of Advection fog
#100. The line connecting A to B crosses what pressure system:
#102. Which coast of the USA is affected by the most frequent hurricanes:
#103. Which of the following would lead to the formation of Steaming fog
Steaming fog, or as it is sometimes called, Arctic Smoke, occurs over sea in polar regions, eg the fjords of Greenland, Iceland and the sea areas of high latitudes. It is caused by cold air from a land mass moving over a warmer moist surface or sea. The small amount of evaporation from the sea is enough to cause saturation and condensation but the air itself must be very stable.
#104. Flying over France at dawn, with 8/8 St at 200ft, QNH 1026, wind Var3, what will be the most likely conditions at mid-day in winter and summer:
#105. When is diurnal variation a maximum?
wind and cloud cover will cause T max to be reduced and T min to be increased.
WIND: wind will cause turbulent mixing of the warm air at the surface with cold air above, reducing T max.
CLOUD: the solar radiation is reflected back by the cloud tops
#106. What do the following one hour interval METARS indicate the passage of: 22010KT 9999 SCT200 14/08 Q1012= 22010KT 9999 OVC200 13/08 Q1011= 23012KT 9KM SCT 060 OVC120 13/08 Q1010= 24012KT 8KM -RA BKN040 OVC090 12/08 Q1009= 25015KT 2000 +RA SCT002 OVC008 12/08 Q1008= 27015KT 0800 DZ BKN002 OVC010 17/16 Q1008= 27015KT 0800 DZ BKN002 OVC010 17/16 Q1008= 27015G30KT 1000 +SHRA TS OVC010 17/16 Q1008= 29020KT 9000 SHRA BKN020 14/07 Q1010= 31020KT 9999 SCTO30 13/07 Q1012=
#107. QNH at Timbuktu (200m AMSL) is 1015 hPa. What is the QFE? (Assume 1 hPa = 8m)
#108. Paris reports OVC 8/8 St at +3 ° C during the day. What will happen on the night of 3/4 Jan
#109. The Arctic Jet core is at:
Arctic Jet Stream: In winters, long polar night cools the polar air forming an arctic air mass between (roughly) 70 deg latitude and poles. The temperature difference between polar and arctic air causes arctic jet stream. The core is at 20,000 feet and max speed around 80 knots.
#110. With a cold front over the North Sea, what weather would you expect 300km behind the front?
#111. If flying cross country at FL50 you first see NS, AS, CC then CI, you can expect:
Warm front approach with cold air ahead
#112. Surface wind is 320/12 what is the wind at 2000ft in the Northern hemisphere?
#113. Which is likely to cause aquaplaning?
Aquaplaning, also known as hydroplaning, is a condition in which standing water, slush or snow, causes the moving wheel of an aircraft to lose contact with the load bearing surface on which it is rolling with the result that braking action on the wheel is not effective in reducing the ground speed of the aircraft.
RA is heavy rain
#114. Lucarno airfield elv 1735 ft altimeter indicates 1310 ft with 1013hPa set what is the QNH?
#115. Prevailing winds in North West. Africa will be
winter north easterly winds
summer sw monsoon
#116. Where is the ITCZ in July?
#117. ATC will only report wind as gusting if:
as per icao annex 3
Annex 3
4. OBSERVING AND REPORTING OF METEOROLOGICAL ELEMENTS […]
4.1 Surface wind […]
4.1.5 Reporting […]
4.1.5.2 In local routine and special reports and in METAR and SPECI: […]c) variations from the mean wind speed (gusts) during the past 10 minutes shall be reported when the maximum wind speed exceeds the mean speed by:
- 2.5 m/s (5 kt) or more in local routine and special reports when noise abatement procedures are applied in accordance with paragraph 7.2.6 of the PANS-ATM (Doc 4444); or
- 5 m/s (10 kt) or more otherwise […]
#118. The letters NC used at the end of a SIGMET, mean:
#119. Hill fog will be most likely when:
#120. On the route London to Bombay, which feature would you most likely encounter between 30E and 50E
#121. In temperate latitudes in summer what conditions would you expect in the centre of a high pressure system?
High pressure area are related to bad visibility and good weather
#122. When would the strongest convection occur?
#123. Above a stable layer in the lower troposphere in an old high pressure system is called:
a high pressure system, air descends at the centre. As the air descends it will be heated adiabatically (more of this later) and will be warmer than the air at a lower level adjacent to the surface. This is called a Subsidence Inversion.
#124. Which way does a depression move?
#125. If the pressure level surface bulges upwards, the pressure system is a:
Pressure level will bulge upwards in high pressure or warm air mass and other way in a low or cold
#126. Freezing rain is most likely from
#127. What is a land breeze?
After sunset. The land will cool rapidly whilst the sea will retain its heat. There will be an increase in pressure at the surface over the land whilst the pressure over the sea will fall – there will be a land breeze. The speed will be about 5 kts and the breeze will extend about 5 nms out to sea.
#128. With regard to RVR and Met vis
#129. When travelling from Stockholm (55N 18E) to Rio de Janeiro (22S 80W), do you encounter:
rio is located at 23° s
stockholm at 59° n
will cross polar and few stj as per the diagram
#130. When are thermal lows most likely
#131. Why does air cool as it rises?
a parcel of air was forced to rise in the atmosphere, the decreasing ambient pressure would cause the parcel to expand, much like an air bubble does when it rises through a champagne glass. As the air rises and expands, it will cool adiabatically.
#132. What is the validity of a significant weather chart
#133. When flying at FL180 in the Southern Hemisphere you experience a left crosswind. What is happening to your true altitude if indicated altitude is constant?
In N hemisphere
Starboard drift= flying into low pressure
Port drift= flying into high pressure
In S hemisphere
Starboard drift= flying into high pressure
Port drift= flying into low pressure
Ac gets starboard drift due to winds from left
Starboard drift
Ac is flying into high pressure
When flying from
Low to high altimeter will under-read
Hence it is under reading the altitude in actual it has increased
#134. What is the main feature of the initial stage of a thunderstorm
#135. In a polar front jet stream in the Northern Hemisphere, where is there likely to be the greatest probability of turbulence?
Polar front jetstreams form in the polar front region in both hemispheres ,in southern around 50° S and near any front which is separate from the polar front.
The upper winds will blow such that looking downstream the cold air will be to the left hand side in northern hemisphere and to the right hand side in the southern hemisphere.
Clear air turbulence (CAT). occurs around the boundaries of jet streams because of the large horizontal and vertical windshears. It is strongest near to, or just below, the jet axis on the cold air (low pressure) side with a secondary area above the axis.
#136. What is haze?
#137. Dew point is defined as:
The dew point or dewpoint of a given parcel of air is the temperature to which the parcel must be cooled, at constant barometric pressure, for the water vapour component to condense into water. The dew point of unsaturated air decreases by approximately 0.5°C per 1,000 ft
The dew point is associated with the relative humidity. A high relative humidity indicates that the dew point is closer to the current air temperature.
#138. On the chart below, where is rain least likely
#139. Flying from Marseilles (QNH 1012) to Palma (QNH 1015) at FL100. You dont reset the altimeter, why would true altitude be the same throughout the flight?
Ac is flying into high pressure
When flying from
Low to high altimeter will under-read
but True altitude is same
The true altitude of this surface will depend on the density of the air below flying from marseille where the qnh is lower to Palma where the qnh is higher you would normally expect your true altitude to increase since true altitude remains constant it must be colder in Palma
#140. On a flight from Zurich to Rome, which of the following METARS would be applicable?
#141. FL180, Northern Hemisphere with a wind from the left, what can you say about temperature with a heading of 360°?
With your back to the upper wind, the cold air is to your left in the northern hemisphere and to your right in the southern hemisphere.
if nose to hdg 360° Wind from left then
north is cold
#142. Which of the following is true about freezing precipitation?
#144. What do the letters NO SIG mean at the end of a METAR
#145. How do you define convection?
Air heated by conduction will be less dense and will therefore rise. This will produce up currents called thermals or convection currents. These currents will help to transfer heat to different parts of the atmosphere. For example, warm air will rise to the upper levels, thus helping to heat the upper atmosphere.
#146. What is a trend forecast
#147. In a class A aircraft if you encounter freezing rain, do you:
Always fly to the warmer layer, be it above or below
#148. How does clear ice form?
supercooled water droplets
Glaze ice or clear ice is formed when LARGE supercooled drops spread over wings
rime ice is formed WHEN SMALL supercooled drops spread over wings
both happen under 0° Celsius flying through clouds
#149. When heading South in the Southern Hemisphere you experience Starboard drift:
With your back to the upper wind, the cold air is to your left in the northern hemisphere and to your right in the southern hemisphere.
#150. Where is windshear the greatest?
#151. When is the latest time radiation fog is most likely?
Radiation fog is caused by radiation of the earth’s heat at night, and the subsequent conductive cooling of the air in contact with the ground to below dew point.
#152. Where do you find squall lines
Squall line with embedded bowing line segments often located along or north of warm front southward across warm sector along or ahead of cold front.
#154. On the chart below, for the route Edinburgh to Zurich, state the optimum flight level.
#155. How does the level of the tropopause vary with latitude in the Northern Hemisphere?
The warmer the air, the higher the tropopause. The colder the air, the lower the tropopause. Generally over the poles, the tropopause can be between 8 -10 km and over the equator 16 – 18 km.
#156. A Fohn wind occurs
The Föhn Wind is a warm dry wind which blows on the downwind side of a mountain range. It is a local wind in the Alps
#157. What is the tropopause?
#158. The Harmattan is
The Harmattan is a cool dusty wind that may reduce visibility to below 1000m, especially in areas bordering desert regions, such as Kano, Nigeria. The dust layer may extend to 7,000 or 10,000 ft or more, visibility improves towards the coast. The Harmattan blows from November through to April, though by this time the winds will be light, especially in the south.
#159. Where do you find the majority of the air within atmosphere?
The Troposphere
This is layer in the atmosphere closest to the earth’s surface and it is defined by the fact that temperature decreases with height by approximately 0.65°C/100 m (1.98°C/1000 ft). It consists of ¾ of the total atmosphere in weight and contains almost all the weather. On average this layer extends from the surface to a 11 km.
#161. What are Lenticularis clouds a possible indication of?
Altocumulus lenticularis, also known as lenticular cloud, is found downwind of mountainous or hilly areas, and is indicative of the presence of mountain wave activity. Because of its position downwind of high ground, moderate or even severe turbulence may be found beneath altocumulus lenticularis. However, the air in the lenticular clouds, themselves, is always smooth.
#162. At what height is half the mass of the atmosphere
#164. How can you determine QNH from QFE
difference between qfe and qnh is elevation
#165. What is the Bora?
The Bora. This wind is part valley and part katabatic. It blows down the north Adriatic with high pressure over Central Europe and the Balkans and a low over the Adriatic. The wind speed is around 70 kts with great gusts exceeding 100 kts in places. The Bora is strongest and most frequent in winter.
#166. What is true about moderate to severe airframe icing
Rain ice occurs in a narrow range of altitudes at low level, about 1000 ft, ahead of a warm front or occlusion and is associated particularly with the moderate continuous rain which often falls from Nimbo Stratus cloud
#167. Where is the 300mb level approx. in ISA?
refer and remember this chart
#168. A winter day in N Europe with a thick layer of SC and surface temperature zero degrees C. You can expect
Radiation Fog can form inland with a slack pressure gradient, principally in Autumn and Winter. With a SW warm moist wind from the Atlantic, advection fog can form over previously cold soaked inland areas. Smoke haze may reduce visibility to the lee of industrial areas. Frontal fog can occur on the warm fronts of deep active Polar Front depressions.
Icing. As over the North Atlantic, icing occurs widely and through great depth in Frontal Cloud and is frequently moderate to severe. Freezing Rain (Rain Ice) can cause severe clear ice in cold air under a warm front or warm occlusion. A rare occurrence in UK, it is more common over Central Europe where the ground is generally much colder, indeed the freezing level may frequently be on the surface especially in the East.
#169. What is the usual procedure when encountering CAT en-route?
In the Air, the presence of a jet will be difficult to SEE, but temperature differences, increases in windspeed, drift and clear air turbulence are all evidence of jet streams.
Clear air turbulence (CAT). occurs around the boundaries of jet streams because of the large horizontal and vertical windshears. It is strongest near to, or just below, the jet axis on the cold air (low pressure) side with a secondary area above the axis.
if you encounter descent immediately
#170. An aircraft flies into an area of supercooled rain with a temperature below zero, what kind of icing is most likely
Glaze ice or clear ice is formed when LARGE supercooled drops spread over wings
rime ice is formed WHEN SMALL supercooled drops spread over wings
both happen under 0° Celsius flying through clouds
#171. When are cyclones most likely?
Tropical revolving storms are known as cyclones in the Bay of Bengal. To form they need a summer warm sea (evidence suggests in excess of 27°C. and the close instability of the ITCZ. In July the ITCZ is north, over the land, so that in this area they form only in early and late summer when the ITCZ is over the sea, that is in June or October.
#172. With regard to the idealized globe below, where are traveling lows located
#173. At a certain position the temperature on the 300 hPa chart is -48°C. According to the chart the tropopause is at FL330. The most likely temperature at FL350 is:
As per isa
Temperature should be
-56.5°C from 11 km (36,090ft) to 20 km (65,617 ft)
but in this hypothetical situation
as per the chart 300 hpa corresponds to fl300 and temperature is-48°c
as per lapse rate -2° c per 1000 feet
at fl330 temp should be -54°C
At tropopause temperature is constant with climb hence
-54°c
#174. If Paris has a surface wind of 160/40, what is the wind at 2000 ft
The surface wind over land is backed by 30 degrees from the geostrophic wind and its speed is reduced by 50%. Hence going up speed will increase and direction will be move towards clockwise
#175. When are the rains most likely in Equatorial Africa?
two ITCZ transits in the year each give their own instability rainfall pattern.
ITCZ passage will be northbound (March/May) and will be followed by the moist SE trade winds from the Indian Ocean. Rainfall will be extensive and is known as the Long Rains.
#176. What causes convection in a low pressure system
#177. What is the likely hazard association with the Harmattan?
The Harmattan is a cool dusty wind that may reduce visibility to below 1000m, especially in areas bordering desert regions, such as Kano, Nigeria. The dust layer may extend to 7,000 or 10,000 ft or more, visibility improves towards the coast. The Harmattan blows from November through to April, though by this time the winds will be light, especially in the south.
#178. What is the cause of the formation of the polar front jet
The Polar Front jets in the northern hemisphere are of a transient na-ture and move with the Polar Front as it moves south in winter and north in summer. Polar Front Jets are caused by the upper pressure gradient between the Tm warm and Pm cold air masses on either side of the polar front.
#179. General surface winds in West Africa with ITCZ to the north:
#180. You are flying at FL120 with a true altitude of 12,000ft, why would this be
#181. In what cloud is icing and turbulence most severe?
#182. TAF 130600Z 130716 VRB02 CAVOK = Volmet 0920 28020G40KT BKN050CB OVC090 TEMPO TS =
#183. What will snow most likely fall from?
#184. Considering the North Atlantic area at 60 N in winter, the mean height of the tropopause is approximately
#185. Rime ice is caused by:
rime ice is formed WHEN SMALL supercooled drops quickly spread over wings
happens under 0° Celsius flying through clouds
#186. An unsaturated parcel of air is forced to rise through an isothermal layer. As long as it stays unsaturated the temperature of the parcel will
Dry or unsaturated air that is either forced to rise or descend within the atmosphere will change its temperature by 1°C per 100 m (3°C/1000 ft). This change of temperature is called the Dry Adiabatic Lapse Rate, (DALR) and it is fixed.
if dry air is disturbed it will rise and cool at the DALR of 1°C/100m and therefore the disturbed air will be colder at 100m than the surroundings
#187. What is the most severe form of icing?
Clear ice is very dangerous. There can be much flowback and the ice appears transparent because there is no air trapped under the flowback icing. The lamination of the ice into layers increases its strength and because it has less air in it this type of ice is much stronger and much harder to remove.
The ice will destroy aerofoil shapes and its weight can cause problems of control because the build-up can be uneven.
Propeller icing can cause severe vibrations and as the ice adheres strongly, when it breaks off, the pieces can be large and cause skin damage.
#188. Cold occlusion is:
The coldest air mass behind and the less cold air in front of the occlusion; the warm air mass is above ground level
#189. Warm occlusion is:
If the air ahead of the warm front is colder than the air behind the cold front, then a warm type occlusion will be formed. This type of occlusion is more common in winter.
#190. Where is the warmest air?
This diagram shows a warm occlusion,
tropical maritime are warm and moist
hence b is warm
#191. What happens to the polar front jet stream in NH winter compared to summer?
Polar Front Jets in the northern hemisphere will move north (and decrease in speed) as the Polar Front moves north in summer. During the winter the Polar Front moves south and because of the greater temperature difference, the speed will increase.
#192. Which is likely to give freezing rain?
Freezing rain occurs when snowflakes pass through a layer of warmer air. They melt down and then passed through a layer of another freezing player because of which they do not have enough time to freeze
in figure b snow flakes go into 5° layer and the -5° layer
#193. Referring to the diagram below the TAF applies best to which aerodrome 19010KT 8000 RA BKN014 TEMPO 1518 4000 RADZ BKN010
Ebbr falls ahead of a warm front
this will be the weather ahead of a warm front
Ahead of a warm front
Surface W/V – Speed increasing, slight backing, usually southerly.
Temperature – Steady low.
Dew Point – Steady low.
Pressure – Steady fall.
Cloud – Increasing to 8/8, base lowering.
Initially cloud changes from Ci to Cs to As, then very close to the front Ns.
Precipitation – Light continuous from As becoming moderate continuous from Ns.
Visibility – Reducing to poor.
#194. Duration of a microburst:
They are concentrated in a burst which is up to 3nm (5km) in horizontal length and have a lifetime of about 5 minutes. (A Macroburst is a similar event but over a bigger area.)
#195. Where is the surface wind usually westerly in a Northern Hemisphere polar front depression?
at position b the winds are westerly which is just in front of the cold front, blue triangles are cold font
#196. Flying from an area of low pressure in the Southern Hemisphere at low altitudes, where is the wind coming from?
Wind flow is clockwise around a low in the S. hemisphere.
Flying away from the L means the wind must be from the left for it to also be flowing clockwise around the low.
Wind flow at Low altitude vs high altitude changes as a result of surface friction preventing flow being truly parallel to the isobars.
The pressure system mentioned is a Low so air will tendflow into the Low, in addition to clockwise around this S. hemisphere Low.
You’re flying away from the low at low altitude (therefore friction effects), the wind has a tendency to flow into the low so there will also be a slight headwind component.
#197. What causes the Geostrophic wind to be stronger than the gradient wind around a low?
Gradient Wind In A Depression If air is moving steadily around a depression, then the centrifugal force opposes the PGF and therefore reduces the wind speed. You can see this on the left hand side of the image shown below.
The gradient wind speed around a depression is less than the geostrophic wind for the same isobar interval. Hence if the Geostrophic Wind Scale (GWS) is used, it will overread.
#198. The subtropical high pressure belt is at which latitude?
#199. A METAR for Paris gave the surface wind at 260/20. Wind at 2000ft is most likely to be:
The surface wind over land is backed by 30 degrees from the geostrophic wind and its speed is reduced by 50% in northern hemisphere,
hence Geostrophic wind of290/40 will reduce by half 15 kts and back by 30° which is 260°
#200. When the upper part of a layer of warm air is advected:
If upper part has cold air that means temperature is decreasing with height
and
If the ELR is greater than 1°C/100 m, the air is unstable – absolute instability.
#201. The QNH at an airfield 200m AMSL is 1009 hPa; air temperature is 10°C lower than standard. What is the QFF?
#202. A plain in Western Europe at 500m (1600ft) AMSL is covered with a uniform alto – cumulus cloud during summer months. At what height AGL is the base of the cloud expected?
Altocumulus usually occur between 8,000 and 15,000 ft with tops on some occasions as high as 23,000 ft. Usually the cloud base is between 6,500 ft and 20,000 ft.
#204. A pilot experiences severe turbulence and icing. A competent met. man would issue:
SIGMET stands for Significant Meteorological Information. A SIGMET is an abbreviated, plain language message, which concerns the occurrence, and/or expected occurrence, of significant weather which may affect the operational safety of aircraft.
#205. Which of these would cause your true altitude to decrease with a constant indicated altitude?
molecules in cold air are closely packed
molecules in warm air are loosely packed
a column of cold air on the left, and a column of warm air on the right. Notice that, since cold air causes pressure to fall more rapidly with height, the pressure levels in the cold air column are compressed towards the Earth’s surface, whereas, in the warm air column, they expand away from the surface
.
If temperature is warmer than ISA
then TRUE > INDICATED
and if it’s colder than ISA
then TRUE < INDICATED.
#206. Flying from Bangkok to Bombay, why does the wind at 30,000ft change from 15kts headwind in winter to a 20kt tailwind in summer?
#208. Where is the ITCZ during the year?
The Intertropical Convergence Zone is the broad zone of separation between the air masses either side of the heat equator. The air is conveyed by the Trade Winds north east and south east. Subject to large seasonal movement overland, but much less over the sea. Sometimes known as the Thermal Equator or Equatorial Trough
The ITCZ follows the sun in that the position varies seasonally. It moves north in the Northern Hemisphere summer and south in the Northern Hemisphere winter. Therefore, the ITCZ is responsible for the wet and dry seasons in the tropics.
#209. Flying from Marseilles to Dakar in summer where is the ITCZ?
dakar and itcz are at same place in summer
this is summer itcz North Africa
#210. Where is the ozone layer?
The Stratosphere
This layer of the atmosphere is defined as that layer above the troposphere where the temperature (more or less) remains constant with an increase in height. (In fact temperature shows a gradual increase with height, especially at the top, where the temperature is zero at 50 km. This is due to the absorption of the sun’s ultra violet radiation by the concentration of ozone at higher levels). The upper boundary to the stratosphere is called the Stratopause. On average the stratosphere layer extends from 11 km to about 50 km.
#211. Which of the following diagrams depicts Cumulus Capillatus:
#212. What wind would you expect between the equator and 20° south?
#214. Where is the most severe weather in a TRS?
#215. Satellite images are used to:
It is often difficult to pick out geographical features, especially when there is thick cloud and of course, areas of oceans are completely featureless. Satellite images are therefore presented with a computer produced graticule of numbered parallels and meridians superimposed. Coastlines may be enhanced as well.
#216. What best describes the diagram below?
it is a polar front depression, which is moving from west to east
#217. A large pressure gradient is shown by:
Pressure gradient is the horizontal rate of change of pressure perpendicular to be isobars directed from high to low pressure it is steep or weak according to the isobars are close or far apart it is said to be steep isobars are closely packed
closer the isobars stronger the winds as wind tend to flow towards low pressure area
#218. The degree of CAT experienced by an aircraft is proportional to:
Clear air turbulence (CAT). occurs around the boundaries of jet streams because of the large horizontal and vertical windshears. It is strongest near to, or just below, the jet axis on the cold air (low pressure) side with a secondary area above the axi
#219. Squall lines are encountered:
Squall lines are observed frequently in the warm sector of a midlatitude cyclone, usually about 100–300 km in advance of the cold front. Divergence ahead of an upper-level trough induces low-level convergence
#220. Microbursts:
They are concentrated in a burst which is up to 3nm (5km) in horizontal length and have a lifetime of about 5 minutes. (A Macroburst is a similar event but over a bigger area.)
#221. Which of the following are described as precipitation?
#222. An aircraft flying in the Alps on a very cold day, RPS 1013 set in the altimeter, flies level with the summit of the mountains. Altitude from aneroid altimeter reads:
If temperature is warmer than ISA
then TRUE > INDICATED
and if it’s colder than ISA
then TRUE < INDICATED.
molecules in cold air are closely packed
molecules in warm air are loosely packed
a column of cold air on the left, and a column of warm air on the right. Notice that, since cold air causes pressure to fall more rapidly with height, the pressure levels in the cold air column are compressed towards the Earth’s surface, whereas, in the warm air column, they expand away from the surface
.
if 1013 is set on a cold day the aircraft will over read elevation than actual
Remember
HIGH LOW HIGH (over read)
WARM COLD OVEREAD
#223. Clouds classified as low level are considered to have a base height of:
#224. With a polar front jet stream (PFJ), the area with the highest probability of turbulence in the Southern Hemisphere is:
Polar front jetstreams form in the polar front region in both hemispheres ,in southern around 50° S and near any front which is separate from the polar front.
The upper winds will blow such that looking downstream the cold air will be to the left hand side in northern hemisphere and to the right hand side in the southern hemisphere.
Clear air turbulence (CAT). occurs around the boundaries of jet streams because of the large horizontal and vertical windshears. It is strongest near to, or just below, the jet axis on the cold air (low pressure) side with a secondary area above the axis.
#225. A after such a fine day yesterday, the ring around the moon indicated bad weather today. Sure enough, it is pouring down rain, with a very low cloud base of uniform grey. It is a little warmer though. This describes:
Approaching ci clouds
Cirrostratus is made up of ice crystals, and lies between 18,000 and 45,000 ft. Cirrostratus is a further warning of an approaching frontal system, and, like altostratus, may cause the Sun and Moon to appear with a halo.
Heavy rain
and dark ns clouds
#226. On a flight from London to New York in summer, where would you cross the ITCZ?
London latitude is 51°
New York latitude is 40 °
position of itcz
#227. What type of low is usually associated with frontal activity?
When a small depression is enclosed within the circulation of a larger depression it is called a secondary. The isobars need not show a closed centre. Secondaries are particularly associated with frontal depressions and form
Travelling Polar Front Lows in the Southern Hemisphere’s disturbed temperate zone will themselves be located well south of the route; but associated troughs, and secondary lows, can bring frontal weather as far north as the Australian South Coast and to New Zealand.
#228. When would you encounter hoar frost?
Hoar frost is a white crystal deposit which appears similar to frost on the ground. It occurs in clear air. Hoar frost will form if the airframe temperature is below 0°C and the ambient temperature is lowered to saturation level.Water vapour in contact with the airframe is converted to ice crystals without becoming liquid, i.e. sublimating.
when temperature from ground increases with increasing height it is called inversion, which means ground is colder or ambient is cold
#229. What is the temperature decrease with height below 11km?
The ICAO ISA is defined as follows:-
a MSL temperature of 15°C
a lapse rate of 0.65°C/100m (1.98° C /1000 ft) up to 11 km (36,090 ft)
a constant temperature of –56.5°C from 11 km (36,090ft) to 20 km (65,617 ft)
after which the temp increases with height ( inversion).
hence lowest is -56.5°
#230. Contours on a weather chart indicate:
A Constant Pressure or Contour Chart is a chart where the pressure is constant everywhere. For example, as shown on the previous page we can see that the 800 mb pressure level varies with height. These heights are plotted as contour lines with the reference being MSL. The heights give us an indication of the distance that a pressure level is from MSL.
Charts are drawn for the following pressure levels:
700 hPa – 10,000 ft
500 hPa – 18,000 ft
300 hPa – 30,000 ft
250 hPa – 34,000 ft
200 hPa – 39,000 ft
100 hPa – 53,000 ft
#231. When do you get TRS at Darwin?
The wet season (November – April)
The wet season in Darwin is characterised by high humidity, monsoonal rains and storms. Average temperatures range from 24.7 – 32 °C (76.5 – 89.6°F), and humidity can push past 80 per cent. The average annual rainfall is 1727.3 mm (68 inches) and January is the wettest month. Despite this, January and February is considered by many as the most beautiful time of year in the Top End. Sunny days and afternoon storms refresh the landscape, and animals and plants flourish.
#232. Equatorial easterly jets
#233. What causes ‘echoes’ on airborne weather radar screens?
The optimum radar frequency is one that has a wavelength comparable to the size of the objects which we wish to detect, namely the large water droplets and wet hail which in turn are associated with severe turbulence; these droplets are about 3 cm across. The typical frequency adopted by most commercial systems is 9375 MHz, /- 30 MHz
#234. In a Tropical Downpour the visibility is sometimes reduced to:
#235. Aircraft with thick wing (T) and thin wing (S) fly at the same TAS and altitude through cloud containing small super cooled water droplets. What extent of icing will be experienced?
#236. What surface weather is associated with a stationary high pressure region, over land, in the winter?
High pressure area are related to bad visibility and good weather,
#237. QNH is defined as:
#238. Where would you expect to find the strongest wind on the ground in temperate latitudes?
As the storm system expands to much larger scale, the action of the Earth’s rotation becomes significant, and, unlike in the small scale low, the airflow is deflected as it is drawn towards the centre of the depression. This deflection of the airflow can result in rotational wind speeds of up to 200 miles per hour
#239. Landing at an airfield with QNH set the pressure altimeter reads:
#240. The fastest moving thunderstorms are:
Thunderstorms usually move in the direction of the 10,000 ft (700 mb) wind, though large storms and newly developed ones may differ from this.
Frontal thunderstorms will often appear along a squall line. This is usually an indication of severe weather. The thunderstorm cells will be in varying stages of development.
#241. Where are the fastest winds in a Tropical Revolving Storm?
#242. What type of cloud is usually found at high level?
#243. You are flying in an atmosphere which is warmer than ISA, what might you expect?
temperature is warmer than ISA
then TRUE > INDICATED
and if it’s colder than ISA
then TRUE < INDICATED.
molecules in cold air are closely packed
molecules in warm air are loosely packed
a column of cold air on the left, and a column of warm air on the right. Notice that, since cold air causes pressure to fall more rapidly with height, the pressure levels in the cold air column are compressed towards the Earth’s surface, whereas, in the warm air column, they expand away from the surface
.
The aircraft will Indicated lower altitude than actual
actual altitude is more than indicated
#244. The environmental lapse rate in the real atmosphere:
in a stationary or static atmosphere under ISA conditions the temperature decreases with height at approximately 0.65°C per 100m. We called this lapse rate the environmental lapse rate (ELR). It is important because this variable lapse rate controls the stability of the air. We also mentioned that the ELR changed from day to day and season to season, sometimes temperature increased with height (inversions) sometimes is was constant with height (isotherms). However, there is another type of temperature change that occurs in our atmosphere that takes place when air is moved.
#245. Sub tropical highs are found:
#246. Airfield is 69 metres below sea level, QFF is 1030 hPa, temperature is ISA -10°C. What is the QNH?
#247. The QNH is 1030Hpa and at the Transition Level you set the SPS. What happens to your indicated altitude?
As we know pressure falls with height, 1013 hpa will be found above 1030 in the atmosphere , if 1013 is at sea level , 1030 is below sea level, with a difference of 17 hpa , every feet is 30 hpa , so 17 hpa is 510 feet,as you can see from the diagram 1013 hpa set on altimeter will give less elevation, it drops by 510 feet
#248. What is the movement of air relating to a trough?
Trough is a low pressure system
In the low pressure area winds converge and there is a vertical movement of air and with abundance of moisture it is the perfect recipe for creation of cloud and bad weather
#249. What is the movement of air relating to a ridge?
Ridge is a high pressure area
in a high pressure are the wind subsides down and diverge
#250. What would the code 01650428 tell you about the condition of the runway?
#251. What time of year is the tornado season in N. America?
Tornado season usually refers to the time of year the U.S. sees the most tornadoes. The peak “tornado season” for the southern Plains (e.g., Texas, Oklahoma, and Kansas) is from May into early June. On the Gulf coast, it is earlier in the spring. In the northern Plains and upper Midwest (North and South Dakota, Nebraska, Iowa, Minnesota), tornado season is in June or July. But, remember, tornadoes can happen at any time of year. Tornadoes can also happen at any time of day or night, but most tornadoes occur between 4–9 p.m.
#252. What is the min. temperature according to ISA?
The ICAO ISA is defined as follows:-
a MSL temperature of 15°C
a lapse rate of 0.65°C/100m (1.98° C /1000 ft) up to 11 km (36,090 ft)
a constant temperature of –56.5°C from 11 km (36,090ft) to 20 km (65,617 ft)
after which the temp increases with height ( inversion).
hence lowest is -56.5°
#253. At a coastal airfield, with the runway parallel to the coastline. You are downwind over the sea with the runway to your right. On a warm summer afternoon, what would you expect the wind to be on finals?
#254. What diagram best shows Acc?
Altocumulus castellanus is a “bubbly” form of normal altocumulus. The “towers” that form in altocumulus castellanus are like battlements on castles, hence the name. These clouds are significant because they often herald a change to showery, thundery weather and are a feature of summer weather in temperate latitudes.
Cumulonimbus clouds sometimes develop from altocumulus castellanus, when instability is present at medium levels of the Troposphere.
#255. What symbol is used to describe wide spread haze?
#256. What symbol is used to describe a TRS?
#257. What symbol is used to describe freezing rain?
#258. The temperature at the surface is 15°C, the temperature at 1000m is 13°C. Is the atmosphere
The ICAO ISA is defined as follows:-
a MSL temperature of 15°C
a lapse rate of 0.65°C/100m (1.98° C /1000 ft) up to 11 km (36,090 ft)
a constant temperature of –56.5°C from 11 km (36,090ft) to 20 km (65,617 ft)
If these conditions prevail atmosphere is stable
#259. Altostratus is
#260. Which of the following would give you the worst airframe icing?
Freezing rain is the most dangerous form of icing and it occurs in rain which becomes supercooled by falling through an inversion into air below 0°C. The supercooled water droplets are now rain sized. The rain does not freeze in the air but once it impacts the aerofoil it freezes to form clear ice with significant flowback.
Freezing rainbuilds up very quickly and a pilot’s action should be to turn onto a reciprocal heading immediately. If the pilot perceives the rain ice very late, then the course of action would be to climb into the warmers layers above. Turning at a late stage into the icing conditions will increase the stall speed and the return journey back out of the rain ice zone will double the ice on the aircraft from when the pilot first elected to turn around.
#261. Small super cooled water droplets hit the aerofoil, will it
Glaze ice or clear ice is formed when LARGE supercooled drops spread over wings
rime ice is formed WHEN SMALL supercooled drops spread over wings
both happen under 0° Celsius flying through clouds
#262. In a METAR you see the coding R16/P1300. What does this imply?
R16 means runway 16
P means plus
it means rvr for runway 16 is more than 1300 metre
#263. If at 0600 the temperature and dew point were recorded as T= – 0.5 and Td = – 1.5, how would a METAR record this?
The temperature shall be separated from the dew point with a solidus “/“. The temperature and dew point shall be coded as two digits rounded to the nearest whole degree Celsius. For example, a temperature of 0.3oC would be coded as “00“. Sub-zero temperatures and dew points shall be prefixed with an M. For example, a temperature of 4oC with a dew point of -2oC would be coded as “04/M02“; a temperature of -0.5oC would be coded as “M00“.
#264. What causes wind?
The uneven heating of the earth’s surface is the main cause of the winds. On being heated more the air raises up and hence low pressure is created. Hence the air in high pressure occupies the low-pressure region causing the wind.
#265. What is the approximate height of the 250hPa level?
Refer the chart
850 hpa is 5000 pressure altitude or fl50
#266. Several aircraft report clear air turbulence in a certain area en route
SIGMET, or Significant Meteorological Information, is a severe weather advisory that contains meteorological information concerning the safety of all aircraft. Compared to AIRMETs, SIGMETs cover more severe weather, hence atc should issue sigmet
#267. What is the flight hazard associated with the Harmattan?
The Harmattan is a cool dusty wind that may reduce visibility to below 1000m, especially in areas bordering desert regions, such as Kano, Nigeria. The dust layer may extend to 7,000 or 10,000 ft or more, visibility improves towards the coast. The Harmattan blows from November through to April, though by this time the winds will be light, especially in the south.
#268. Where are icing conditions on a runway specified?
an additional 8 figure runway state code will be specified on the metar if there is any contamination
#269. Where are icing conditions on route specified?
Significant Weather (SIGWX) charts provide invaluable meteorological information to aircraft operators and flight crew. Particularly for longer flights, or when weather issues may be a factor, SIGWX charts can be a vital flight planning tool.
the only cloud shown in waf sigwx chart is CB moderate and severe icing is associated to a cb
#270. If flying in the Alps with a Foehn effect from the south
The Föhn Wind is a warm dry wind which blows on the downwind side of a mountain range. It is a local wind in the Alps.
If moist air is forced to rise up a mountain side, it will quickly become saturated and will cool adiabatically as it rises. After reaching the condensation level, cloud will form and the air will cool at the SALR
#271. If flying en route and you encounter moderate turbulence with convective clouds and you decide to continue, you should
Decreasing the speed will give more allowance for the thrust and we can climb faster
#272. You are flying from Madrid (QNH 1012) to Paris (QNH 1015) at FL 80. If your true altitude and indicated altitude remain the same then
The true altitude of this surface will depend on the density of the air below flying from Madrid where the qnh is lower to ,Paris where the qnh is higher you would normally expect your true altitude to increase since true altitude remains constant it must be colder in Paris
#273. If you are flying on a QNH 1009 on very cold day and you circle the top of a peak in the Alps, your altimeter will read
Disregard the qnh
Let’s say if we are flying visually
on a cold day or a warm day
if you fly over a mountain keeping clear of terrain visually, you will be at the same altitude,
Now bring in the qnh
on a cold day
if you fly over a mountain keeping clear of terrain visually, setting qnh 1009 on the altimeter , indicated altitude will be more than the true altitude
on a warm day
if you fly at the same altitude visually ,setting qnh 1009 on the altimeter , indicated altitude will be less than the true altitude
Because
molecules in cold air are closely packed
molecules in warm air are loosely packed
a column of cold air on the left, and a column of warm air on the right. Notice that, since cold air causes pressure to fall more rapidly with height, the pressure levels in the cold air column are compressed towards the Earth’s surface, whereas, in the warm air column, they expand away from the surface
.
#274. squall line
ICAO “No change of course and altitude necessary” recommendation be followed? — “Light”
ICAOs change of course and/or altitude “desirable recommendation” be followed? — “Moderate”
ICAOs change of course and/or altitude “immediately instruction” be followed? — “Severe”
#275. Aircraft A has a sharp leading edge and a thin aerofoil. Aircraft B has a thick cambered wing aerofoil. If they are flying at the same TAS into clouds with small super cooled water droplets then
#276. What is subsidence?
#277. If an Isohypse on a surface pressure chart of 500hPa shows a figure of 522, this indicates
lines of equal thickness are plotted on chart also called the isohypse
thickness level are measured in decameter or dam
520 dam is 5200 metres
#278. Moderate turbulence can be expected in
Nimbostratus is a dense, dark-grey, rain-bearing, stratiform cloud, producing extensive and long-lasting continuous precipitation. Usually the cloud base is between the surface and 10,000ft above ground level.
#279. The polar front jet stream in summer compared to winter in the Northern Hemisphere moves
Polar Front Jets in the northern hemisphere will move north (and decrease in speed) as the Polar Front moves north in summer. During the winter the Polar Front moves south and because of the greater temperature difference, the speed will increase.
#280. The Bora is a
The Bora. This wind is part valley and part katabatic. It blows down the north Adriatic with high pressure over Central Europe and the Balkans and a low over the Adriatic. The wind speed is around 70 kts with great gusts exceeding 100 kts in places. The Bora is strongest and most frequent in winter.
#281. RVR is
The maximum distance in the direction of takeoff or landing at which the runway, or specified lights delineating the runway, can be seen from a position on the centreline corresponding to the average eye level of a pilot at touchdown.
– RVR is not normally reported if it is 1500m or more.
– Between 1500 and 800m it is reported in steps of 100m.
– Between 800 and 200m it is reported in steps of 50m.
– Between 0 and 200m it is reported in steps of 25m.
– e.g. R36L/P1500: Runway 36 Left touch-down RVR is more than 1500m.
The lowest visibility observed will be reported if the visibility in any direction is
a) Less than 1500 metres
or
b) Less than 50% of the prevailing visibility.
RVR is not normally reported if it is 1500m or more
the reported value of RVR is typically higher than the associated visibility value.
These findings are consistent with the fact that the assessment of RVR takes advantage of high intensity runway lights while the visibility assessment is based upon lights of moderate intensity.
#282. Comparing the surface wind to the 3000ft wind
The Geostrophic Wind only blows above the friction layer. Within the friction layer the wind speed is reduced because of surface friction. Therefore the Coriolis Force will reduce, causing the two forces to be out of balance. Remember that the friction layer varies depending upon the nature of the surface and the time of the day. There-fore, the height of the Geostrophic Wind will vary. Generally though it is considered to be between 2,000 – 3,000ft.
Since surface friction has reduced the wind velocity, resulting in a reduction in the Coriolis Force, the PGF is now more dominating. This causes the wind to blow across the isobars towards the low.
#283. In which air mass can extreme cold temperatures be found?
If the airmass is lying over a warm tropical ocean, the airmass is classified as Tropical Maritime (TM).
If the airmass lies over a cold continent in winter, the airmass is classified as Polar Continental (PC).
#284. Up and down going draughts in a thunderstorm occur in which stage?
#285. Relative humidity increases in
As the air descends it will be heated adiabatically and will be warmer than the air at a lower level adjacent to the surface.
as the temperature increases, the relative humidity will decrease
vice averse
temp decreases rh increases
#286. Super cooled water droplets are found in
Supercooled water droplets can exist in clouds at temperatures as low as -40°C.
Freezing fog is an example of supercooled drops in fog
freezing rain is an example of supercooled drops in precipitation
#287. Which of the following, with no Orographic intensification, will give rise to light to moderate icing conditions?
Orographic Lifting occurs when air is forced to rise and cool due to terrain features such as hills or mountains. If the cooling is sufficient, water vapor condenses into clouds. Additional cooling results in rain or snow
WHEREAS ALTOSTRATUS CLOUDS AND ALTO CUMULUS
Altostratus clouds form when a large mass of warm air rises, causing water vapor in the atmosphere to condense onto nuclei (small dust particles), forming water droplets and ice crystals. These conditions usually happen at the leading edge of a warm front, where cirrostratus clouds thicken and lower until they transition into altostratus clouds
Altocumulus clouds can form in several ways, such as;
- Formation through the breakup of altostratus
- The lifting of moist air pockets which are cooled by gentle turbulence
These 2 types of cloud are medium level cloud and have light to moderate level of icing and are not produced by orographic lifting
#288. If an active cold front is approaching what will the altimeter read on a parked aircraft shortly before the front arrives?
As the cold air advances, it forces the warm air upwards causing the warm air to cool. The water vapour in the warm air mass, consequently, condenses, and clouds are created. The slope of the cold front boundary is steeper than that of the warm front, with a gradient of approximately one in fifty.
The unstable air just ahead of the cold front is, forced to rise vigorously. Causing pressure to reduce and altimeter reading increased
#290. What would be reflected to radar?
hail causes echo on AIR BORNE WEATHER RADAR
The optimum radar frequency is one that has a wavelength comparable to the size of the objects which we wish to detect, namely the large water droplets and wet hail which in turn are associated with severe turbulence; these droplets are about 3 cm across. The typical frequency adopted by most commercial systems is 9375 MHz, /- 30 MHz
#291. A jet stream with a wind speed of 350kts
The direction of jet streams is generally westerly, maximum speeds occur near the tropopause, 200 kts have been recorded in Europe/N Atlantic and 300 kts in Asia.
In equatorial regions there are however some easterly jets
#292. Turbulence is worst in a Jet stream
Clear air turbulence (CAT). occurs around the boundaries of jet streams because of the large horizontal and vertical windshears. It is strongest near to, or just below, the jet axis on the cold air (low pressure) side with a secondary area above the axis.
#293. If you fly at right angles to a jet stream in Europe with a decreasing outside air temperature, you will experience
With your back to the upper wind, the cold air is to your left in the northern hemisphere and to your right in the southern hemisphere.”
#294. Low level wind shear is likely to be greatest
Vertical windshear is change in wind velocity with height. It is typically measured in knots per 100ft. This type of windshear is very common during an inversion, therefore expect them at night and in well developed high pressure systems such as those found under the sub tropical high pressure belt. As an aeroplane fly’s through an inversion, not only will the change of temperature cause the engine performance to change, but the abrupt change in wind speed and direction may significantly alter the flight path
#295. The North African rains occur
#296. TEMPO TS indicates
TEMPO, means that the change is temporary, and that the different conditions will prevail for periods of less than one hour, only, and no more than half the time period
ts means thunderstorm
#297. What happens in a warm occlusion?
#299. A mass of unsaturated air is forced to rise till just under the condensation level. It then settles back to its original position
If an unsaturated parcel of air rises (either because it’s buoyant or it is forced to do so) it will cool adiabatically. This cooling increases the relative humidity of the parcel of air until eventually the temperature of parcel has reached dew point temperature and the relative humidity will be 100%.At this point the air parcel is saturated and further ascent and cooling will cause condensation and cloud to form. The level in the atmosphere at which this happens is called the condensation level. It usually marks the base of any cloud formations
but his all happens when it reaches the condition level
in this case it doesn’t reach the condensation level and descends back to its original position
If the lifted air’s lapse rate (either dry or saturated) is the same as the environmental lapse rate then we have neutral stability. This is because the temperature change of the lifted air will be the same temperature change as the environmental air. Therefore, at every level the air is forced to rise, it will have the same temperature as the surrounding air and therefore the same density. As a result the air will remain where it is displaced to.
#301. What is a microburst?
the mass of air descending from the cloud is significant enough, a phenomenon known as a microburst
#302. The high bringing tropical continental air masses to Europe in summer
Tropical Continental
Source: N Africa, SE Europe and the Balkans. Mainly summer, warm, dry, stable.
#303. What most likely gives freezing rain over Central Europe?
As over the North Atlantic, icing occurs widely and through great depth in Frontal Cloud and is frequently moderate to severe. Freezing Rain (Rain Ice) can cause severe clear ice in cold air under a warm front or warm occlusion. A rare occurrence in UK, it is more common over Central Europe where the ground is generally much colder, indeed the freezing level may frequently be on the surface especially in the East.
#304. Which of the cuts in the plan view of the polar front depression best represents the profile view?
Looking at the above plan view you can see a typical polar front depression on the polar front. Notice the intrusion of the tropical maritime air creating the characteristic wedge shape which we call the warm sector. To the right of the warm sector, you can see the warm front. This part of the polar front is marked with red semicircles to signify that warm air is overriding and replacing cold air. To the left of the warm sector you can see the cold front. This part of the polar front is marked with blue triangles to signify that cold air is undercutting and replacing warm.
#305. On a polar front depression, the point of occlusion moves mainly in which direction in the Northern Hemisphere?
These depressions are called the Polar Front Depressions or Warm Sector Depressions and they move west to east along the polar front with the general westerly upper winds, reaching NW Europe from the Atlantic Ocean
#306. In the Northern Hemisphere between lat. 35°N – 65°N in the north Atlantic during winter, the principle land based depression affecting the region is located at
Icelandic low, large persistent atmospheric low-pressure centre that forms between Iceland-and southern Greenland. It often causes strong winter winds over the North Atlantic Ocean. In winter the ocean is considerably warmer than the continents, and this difference is responsible for the location of the Icelandic low, which dominates the wind circulation over the North Atlantic
#307. The ITCZ is best described as
The Intertropical Convergence Zone is the broad zone of separation between the air masses either side of the heat equator. The air is conveyed by the Trade Winds north east and south east. Subject to large seasonal movement overland, but much less over the sea. Sometimes known as the Thermal Equator or Equatorial Trough.
#308. When would you most likely find cold occlusions across central Europe?
the air behind the cold front is colder than the air ahead of the warm front, then a cold type occlusion will be formed. This type of occlusion is more common in summer.
#309. Clear ice is most likely to form
Glaze ice or clear ice is formed when LARGE supercooled drops spread over wings
rime ice is formed WHEN SMALL supercooled drops spread over wings
both happen under 0° Celsius flying through clouds
large supercool water sustain only between 0 to -20 degree
#310. How do you calculate the lowest flight level?
owest forecast QNH provided by the Met. Office, is used to ensure safe terrain clearance. It is the value below which QNH is forecast not to fall in a given period and area.
The value should be lower than the actual QNH anywhere in the area, and if set on the sub-scale, regional QNH will cause the altimeter to under-read
(the altimeter showing aircraft to be lower than it actually is).
#311. TRS off Somalia are called
TRS are given different names in different parts of the world. Either side of North America these storms are called Hurricanes. In the Indian Ocean and around Australia they are called Cyclones and around the far east, they called Typhoons. Typhoons are the most violent and have the longest season of any TRS.
Indian Ocean touches Somalia
#312. Which cloud would you encounter the most intensive rain?
Nimbostratus is a dense, dark-grey, rain-bearing, stratiform cloud, producing extensive and long-lasting continuous precipitation. Usually the cloud base is between the surface and 10,000ft above ground level.
#313. What height is the tropopause and at what temperature?
Since temperature decreases with height it goes to follow that the temperature at the tropopause is controlled by its height. The higher it is, the colder the temperature at the tropopause. The lower it is, the warmer the temperature at the tropopause. The temperature at the tropopause can be as high as -40°C over the poles and as low as -80°C over the equator. However, on average the tropopause is at about 11 km where its temperature is -56.5°C.
#314. Where do you get freezing rain?
Freezing rain occurs when the layer of freezing air is so thin that the raindrops do not have enough time to freeze before reaching the ground. Instead, the water freezes on contact with the surface, creating a coating of ice on whatever the raindrops contact.
#315. Flying from Dakar to Rio de Janeiro in winter where would you cross the ITCZ?
#316. Where are polar front depressions located?
Polar front depressions are found along the polar front which lies principally in the higher latitudes at about 40º to 60°, North and South, depending upon the season. You can see these two bands of low pressure in near the top and bottom of the globe. The depressions typically move from West to East across the Earth’s surface, and the process of their formation is complex.
#319. With low pressures dominating the Med, which of the following would likely be found in central Europe?
in the diagram above low pressure in Mediterranean gives bora winds in Central Europe
Bora wind are part valley and part katabatic. It blows down the north Adriatic with high pressure over Central Europe and the Balkans and a low over the Adriatic. The wind speed is around 70 kts with great gusts exceeding 100 kts in places. The Bora is strongest and most frequent in winter.
examples of warm Katabatic winds are the Föhn, Chinook, Bergwind and Diablo.
#320. Which of the following will give the greatest difference between temperature and dew point?
If the RH is less than 100% then the air is considered to be dry
The dew point or dewpoint of a given parcel of air is the temperature to which the parcel must be cooled, at constant barometric pressure, for the water vapour component to condense into water.
A high relative humidity indicates that the dew point is closer to the current air temperature. If the relative humidity is 100%, the dew point will be equal to the current temperature. The dew point can never be more than the ambient temperature.
If the RH is less than 100% then the air is considered to be dry hence dry air will have the greatest difference
#321. CB cloud in summer contains
Cumulonimbus clouds are clouds that the aviator should avoid. Cumulonimbus clouds consist of vigorous convective cloud cells of great vertical extent. In the later stages of their development, cumulonimbus clouds display a characteristic anvil top, as the upper part of the cloud hits the Tropopause. The upper parts of a cumulonimbus cloud often consist of super-cooled water droplets and ice crystals. The base of cumulonimbus clouds is often very dark, with ragged cloud appearing beneath the main cloud cell. Usually the cloud base is between 2,000 ft and 5,000 ft.
#322. Using the diagram below you are on a flight from A to B at 1500 ft. Which statement is true?
A= closely packed iso bars indicate low pressure
B= Widely spaced isobars indicate high pressure
flying from low to high pressure true altitude will increase
#323. Solar radiation heats the atmosphere by
#324. How are CBs that are not close to other CBs described on a SIGMET?
EMBD for close cb
ISOL for isolated cb
#325. When do you mainly get cold occlusions?
the air behind the cold front is colder than the air ahead of the warm front, then a cold type occlusion will be formed. This type of occlusion is more common in summer.
#326. A coded SIGMET message for Athens reads “TS W Athenia MOV E”
TS – means thunderstorm
W – means coming from west
Athenia- (it means meant for athens)
MOV E- means moving east
#327. In a very deep depression in Iceland, the likely weather is
depression means low pressure system like cyclone or thunderstorm
relates to high wind, rain, snow
#328. What affects how much water vapour the air can hold?
This amount of space in the air that can hold water changes depending on the temperature and pressure.
The maximum amount of water vapour that can be in the air depends on the air temperature
#329. In a METAR/TAF what is VV?
If the sky at an aerodrome is obscured for reasons other than cloud cover, and cloud coverage cannot easily be determined, the code VV is used in place of the cloud information. VV is followed by the vertical visibility in hundreds of feet
#330. In an METAR the cloud height is above
The height above aerodrome level of the lowest layer of cloud of more than 4 oktas”
#331. Aerodrome at MSL, QNH is 1022. QFF is
#332. Air at the upper levels of the atmosphere is diverging. What would you expect at the surface?
upper level divergence means lower level convergence , hence low pressure system
#333. What happens to the stability of the atmosphere in an inversion? (Temp increasing with height)
Air is stable whenever the ELR is less than 0.6°C/100m.
In inversion ELR is less than 0.6°C/100m.as temp increases with height
#334. What happens to stability of the atmosphere in an isothermal layer? (Temp constant with height)
Air is stable whenever the ELR is less than 0.6°C/100m.
In isotherm lapse rate is 0 as temp remains same
#335. Air temperature in the afternoon is +12°C with a dew point of +5°C. What temperature change must happen for saturation to occur?
When temperature and dew point are same saturation occurs and fog formation takes place
#336. What is the gradient of a warm front?
#337. Subsidence would be described as
subsidence occurs in high pressure
#338. What is the technical term for an increase in temperature with altitude?
- Inversion is also called negative lapse rate
Where the temperature increases with an increase in height, then we have what is called an inversion. We have already seen that at night we can expect an inversion above the surface, but this can occur in many different ways.
#339. What units are used to measure vertical wind shear?
Vertical windshear is change in horizontal wind velocity with height. It is typically measured in knots per 100ft.
Horizontal windshear is change in wind velocity with horizontal distance and is common with the passage of fronts
#340. The Pampero is
The pampero is a burst of cold polar air from the west, southwest, or south on the pampas in the south of Brazil, Argentina, Uruguay, Paraguay and Bolivia
#341. If you fly from Bombay to Karachi in summer you might experience a 70kt tailwind and the same flight in winter experiences a headwind. This is due to
in winters aircraft flying to the west from bombay will experience western disturbance , headwind
in summer you will experience tropical easterly jet stream
#342. Why is the “Icelandic low” more intense in winter?
celandic low, large persistent atmospheric low-pressure centre that forms between Iceland-and southern Greenland. It often causes strong winter winds over the North Atlantic Ocean. In winter the ocean is considerably warmer than the continents, and this difference is responsible for the location of the Icelandic low, which dominates the wind circulation over the North Atlantic
#343. What causes the formation of aircraft contrails at certain altitudes?
#344. QNH is 1003. At FL100 true altitude is 10,000ft. Is it
o know the temperature of the air you need to know two things, the indicated altitude on QNH and the true altitude. You know this because if it’s warmer than ISA
then TRUE > INDICATED
and if it’s colder than ISA
then TRUE < INDICATED.
In the question then, whilst you have the true altitude they have not given you the indicated on QNH. They have given you a flight level which you can use to work out the indicated on QNH. So, get off the flight level 1013 and onto 1003.
You now see that the INDICATED on QNH is 9730 FT. Notice that this is less than the TRUE altitude of 10,000ft. Therefore the TRUE altitude is more than the INDICATED altitude.
Looking back to the second paragraph this can only happen if the air is warmer!
#345. Winds in western India
#346. Ice pellets on the ground are evident that
#347. You have to fly through a warm front. The freezing level in the warm air is at 10,000ft and the freezing layer in the cold air is at 2,000ft. Where are you least likely to encounter freezing rain?
level at which temperature is zero is called freezing level
freezing rain occurs when falls from an inverion layer into an area below 0 deg celsius
rain in the warm air falls from above 10000 feet as 10000 feet is freezing level
12000 feet can be considered inversion as it is warmer being in the warmer sector
#348. You are flying at FL170. The pressure level which is closest to you is the
Refer the chart
500 hpa is 18000 pressure altitude
#349. When you have icing conditions forecast on-route, on what chart would you find this information?
ignificant Weather (SIGWX) charts provide invaluable meteorological information to aircraft operators and flight crew. Particularly for longer flights, or when weather issues may be a factor, SIGWX charts can be a vital flight planning tool.
the only cloud shown in waf sigwx chart is CB moderate and severe icing is associated to a cb
#350. The average duration of a microburst
They are concentrated in a burst which is up to 3nm (5km) in horizontal length and have a lifetime of about 5 minutes. (A Macroburst is a similar event but over a bigger area.)
#351. How is QFE determined from QNH?
#352. Which cloud would produce showers?
Cumulonimbus clouds are clouds that the aviator should avoid. Cumulonimbus clouds consist of vigorous convective cloud cells of great vertical extent. In the later stages of their development, cumulonimbus clouds display a characteristic anvil top, as the upper part of the cloud hits the Tropopause. The upper parts of a cumulonimbus cloud often consist of super-cooled water droplets and ice crystals.
Within cumulonimbus, very strong upcurrents and downdraughts are continually at play, producing severe precipitation in the form of heavy showers of rain and hail.
#354. QFE is 1000hPa with an airfield elevation of 200m AMSL. What is QNH?
1 metre above msl pressure reduces by 8 hpa
200 metre above msl pressure increases by 25 hpa
Current pressure 1000 plus 25 gives qnh
#355. With the approach of a warm front
as in the table pressure falls
hence qfe and qnh will fall
#356. With the approach of a cold front, temperature will
temperture remains the same With the approach of a cold front as the leading air mass is warm
#357. On a surface weather chart, isobars are lines of
QFF is The value of pressure reduced to MSL in accordance with isothermal conditions.
Isobars are line joining places of the same atmospheric pressure (usually MSL pressure QFF).
#358. What is the effect of a strong low level inversion?
Vertical windshear is change in wind velocity with height. It is typically measured in knots per 100ft. This type of windshear is very common during an inversion, therefore expect them at night and in well developed high pressure systems such as those found under the sub tropical high pressure belt. As an aeroplane fly’s through an inversion, not only will the change of temperature cause the engine performance to change, but the abrupt change in wind speed and direction may significantly alter the flight path.
#359. A moist stable air mass is forced to rise against a mountain range. What might you expect?
#360. Air temperature is 12°C, Dew point is 10°C and the sea temperature is 8°C. What might you expect if the air is blown over the sea?
#361. A cold pool over land in summer would give rise to:
These are outbreaks of cold air from near the poles. These outbreaks are usually characterized by a cold front at their leading edge.
Although surface temperature anomalies such as cold pools are not evident on surface pressure charts, they can be found most notably by looking at pressure charts in the middle to upper atmosphere. You may remember that cold air causes pressure to fall more rapidly with height, reducing the pressure in the upper atmosphere. Therefore by analyzing a pressure chart in the middle to upper atmosphere you can identify cold air pools by the low pressure they create,
Low pressure is accompanied by showers and thunderst
#362. Near industrial areas with lots of smoke what the worst situation is for met vis:
- Temperature inversion, also called thermal inversion, a reversal of the normal behaviour of temperature in the troposphere (the region of the atmosphere nearest Earth’s surface), in which a layer of cool air at the surface is overlain by a layer of warmer air. (Under normal conditions air temperature usually decreases with height.)
- Inversions play an important role in determining cloud forms, precipitation, and visibility.
- An inversion acts as a cap on the upward movement of air from the layers below.
- As a result, convection produced by the heating of air from below is limited to levels below the inversion.
- Diffusion of dust, smoke, and other air pollutants is likewise limited.
#363. Upper level winds are forecast in significant weather charts as:
Wind speed is usually given in knots, but some countries give the speed in metres per second and the Met.
Wind direction is always given as the direction from which the wind is blowing. It is normally given in degrees true, but wind direction given to a pilot by ATC or in an ATIS will be given in degrees magnetic
#364. Melbourne in July will experience:
#365. How often are METAR’s issued at Main European Airfields?
metar is issued every 30 minutes almost everywhere in the world
#366. METAR winds are meaned over the………….. period immediately preceding the time of observation.
Wind speed – coded as two or three digits (08) immediately follows the wind direction. Wind speed is determined by averaging the speed over a 10-minute period and is coded in whole knots (kts).
#367. Main TAF’s at large aerodromes are valid for approximately:
Terminal Aerodrome Forecasts (TAFs) are forecasts of meteorological conditions at an aerodrome, as opposed to the report of actual, present conditions as given in a METAR.
TAFs usually cover a period of between 9 and 24 hours.
9-hour TAFs are issued every 3 hours, and 12 to 24-hour TAFS every 6 hours.
#368. What are the TRS of the west coast of Africa called?
#369. The most severe in-flight icing occurs in:
Freezing rain is the most dangerous form of icing and it occurs in rain which becomes supercooled by falling through an inversion into air below 0°C. The supercooled water droplets are now rain sized. The rain does not freeze in the air but once it impacts the aerofoil it freezes to form clear ice with significant flowback.
Freezing rainbuilds up very quickly and a pilot’s action should be to turn onto a reciprocal heading immediately. If the pilot perceives the rain ice very late, then the course of action would be to climb into the warmers layers above. Turning at a late stage into the icing conditions will increase the stall speed and the return journey back out of the rain ice zone will double the ice on the aircraft from when the pilot first elected to turn around.
#370. Which of the following constituents in the atmosphere has the greatest effect on the weather?
THE CONSTITUENTS OF THE ATMOSPHERE
Nitrogen 78 % Argon 0.95% Oxygen 21 % Carbon Dioxide 0.05%
Plus traces of:
Neon Nitrous Oxide Helium Nitrogen Dioxide Krypton Carbon Monoxide Xenon Sulphur Dioxide Hydrogen Ammonia Methane Iodine and Ozone Water Vapour
Of all the trace gases, water vapour is by the far the most significant. Without it there would be no weather.
#372. RVR is defined as being
RVR is the maximum distance that a pilot 15 ft above the runway in the touchdown area can see marker boards by day or runway lights by night when looking in the direction of take-off or landing
RVR is reported when normal visibility is 1500 m or less, or when shallow fog is reported or forecast
#373. What type of cloud extends into another level?
Nimbostratus is also a medium-level cloud, but it may also extend into both the lower and upper levels of the atmosphere
#374. Ceilometers measure
As the name suggests “CLOUD CIELING” or height
#375. In a METAR, the pressure group represents
QNH values are given in hectopascals (HPA) rounded down to the nearest lower whole hectopascal
#376. On a Station circle decode, the cloud cover is divided into
8 parts also called oktas
#377. Which of the following is true? QNH is:
Qnh is 1013 only under isa conditions
which is hypothetical
#378. When does Darwin (Australia. experience TRS?
The wet season (November – April)
The wet season in Darwin is characterised by high humidity, monsoonal rains and storms. Average temperatures range from 24.7 – 32 °C (76.5 – 89.6°F), and humidity can push past 80 per cent. The average annual rainfall is 1727.3 mm (68 inches) and January is the wettest month. Despite this, January and February is considered by many as the most beautiful time of year in the Top End. Sunny days and afternoon storms refresh the landscape, and animals and plants flourish.
#379. Radiation fog extends from the surface to:
Radiation fog is caused by radiation of the earth’s heat at night, and the subsequent conductive cooling of the air in contact with the ground to below dew point.
If there is a light wind, then fog will form, in calm conditions the result will be the formation of dew. The fog is not usually more than a few hundred feet thick.
#380. Flying from Marseilles to Palma you discover your true altitude is increasing, but oddly the QNH is identical at both places. What could be the reason?
If temperature is warmer than ISA
then TRUE > INDICATED
and if it’s colder than ISA
then TRUE < INDICATED.
#381. Hurricanes in the Caribbean generally move
HURRICANE IS THE NAME GIVEN TO TRS IN THE CARIBBEAN /GULF OF MEXICO AREA. FREQUENCY OF HURRICANES IS 3 PER YEAR FROM AUGUST TO OCTOBER
THEY TRAVEL WESTWARDS 10-15 DEG NORTH LAT
THEN THEY CROSS BAY OF MEXICO OR TURN RIGHT ALONG SUB TROPICAL HIGHG TO TRACK
NW,N,NORTH EAST UP THE USA COAST
#382. Low level inversions
In a HIGH there is divergence of wind to low pressure region ,there is no vertical movement of air and fog mist or haze stands still hence poor visibility
inversion occurs in high
#383. What are the TRS off the coast of Madagascar called and when would you expect to find them?
TRS are given different names in different parts of the world. Either side of North America these storms are called Hurricanes. In the Indian Ocean and around Australia they are called Cyclones and around the far east, they called Typhoons. Typhoons are the most violent and have the longest season of any TRS.
Indian Ocean touches MADAGASCAR
December and January Has high humidity and trade winds hence trs forms during this time
#384. A forecast trend
TREND forecast is valid for 2 hours after the time of the observation of the METAR, and constitutes the final section of the METAR. The change in weather conditions indicated by the code, TREND, can be further qualified by the codes, BECMG, meaning becoming, or TEMPO meaning temporarily.
#386. QNH is 1030. Aerodrome is 200m AMSL. What is QFF?
#387. Where are down draughts predominant in a thunderstorm?
#388. If an Aerodrome is 1500ft AMSL on QNH 1038, what will the actual height AGL to get to FL75?
Under normal conditions, pressure varies by 1 hPa per 27 feet.
1038 hPa is (1038-1013.25) = 24.75 hPa higher than standard
24.75 x 27 = 668.25 ft
So FL75 will be at 7500 plus 668.25 = 8168.25 ft msl
So, 8168.25 – 1500 = 6668.25 ft agl, rounded up to 6670 ft agl
#389. What is FG VV100?
VV IS vertical visibility
100 is in feet as the visibility is always in feet not metre
#390. The line connecting C to D crosses which type of front?
triangles,are the standard symbols denoting a cold front.
semi-circular Are denoting warm front
#391. What is B?
A col, also called saddle point or neutral point, is in meteorology, the point of intersection of a trough and a ridge in the pressure pattern of a weather map. It takes the form of a saddle where the air pressure is relatively higher than that of the low-pressure regions
#392. On a particular day the PFJ runs north to south in the Northern Hemisphere
Polar front jetstreams form in the polar front region in both hemispheres ,in southern around 50° S and near any front which is separate from the polar front.
The upper winds will blow such that looking downstream the cold air will be to the left hand side in northern hemisphere and to the right hand side in the southern hemisphere.
polar air is cold air hence if pfj travels south polar air will be east
#393. A 350 kt jet stream is
The direction of jet streams is generally westerly, maximum speeds occur near the tropopause, 200 kts have been recorded in Europe/N Atlantic and 300 kts in Asia.
In equatorial regions there are however some easterly jets.
#394. Why do TRS tend to form in the western side of tropical oceans?
#395. Where would an anemometer be placed?
Surface wind is measured by a wind vane which aligns itself with the wind direction, and an anemometer which measures the speed. An anemometer is a set of 3 hemispherical cups which rotate on a shaft with the effect of the wind. The speed of rotation of the shaft is directly proportional to the windspeed. The rotation is used to drive a small generator, the output of which is then displayed on a gauge which is calibrated in knots.
Both vane and anemometer are positioned 33 ft (10 m) AGL and they are located clear of buildings and obstructions which could affect the airflow and hence accuracy. An anemograph records windspeed and sometimes direction.
#396. Altimeter set to 1023 at aerodrome. On climb to altitude the SPS is set at transition altitude. What will indication on altimeter do on resetting to QNH?
Forget about the part in which aircraft is at aerodrome with 1023 setting
at pressure altitude
altitude Measured from 1013 (SPS)setting
will be less than altitude measured at 1023 setting
#397. 90km/hr wind in kts is:
90 km = 48.6 nautical mile
#398. The ITCZ is best described as:
The Intertropical Convergence Zone is the broad zone of separation between the air masses either side of the heat equator. The air is conveyed by the Trade Winds north east and south east. Subject to large seasonal movement overland, but much less over the sea. Sometimes known as the Thermal Equator or Equatorial Trough.
#399. When landing at Dakar in July, the weather to be expected is:
#400. When is the Hurricane season in the Caribbean?
TRS are given different names in different parts of the world. Either side of North America these storms are called Hurricanes. In the Indian Ocean and around Australia they are called Cyclones and around the far east, they called Typhoons. Typhoons are the most violent and have the longest season of any TRS.
Indian Ocean touches MADAGASCAR
november December and January Has high humidity and trade winds hence trs forms during this time
#401. An aircraft is stationary on the ground. With the passage of an active cold front its altimeter will show:
PRESSURE WILL FALL , ALTIMETER INCREASE
PRESSURE WILL RISE , ALTIMETER DECREASE
#402. What is the average vertical extent of radiation fog?
Radiation fog is caused by radiation of the earth’s heat at night, and the subsequent conductive cooling of the air in contact with the ground to below dew point.
If there is a light wind, then fog will form, in calm conditions the result will be the formation of dew. The fog is not usually more than a few hundred feet thick.
#403. Where is clear ice most likely in a Cb?
Glaze ice or clear ice is formed when LARGE supercooled drops spread over wings
rime ice is formed WHEN SMALL supercooled drops spread over wings
both happen under 0° Celsius flying through clouds
large supercool water sustain only between 0 to -20 degree
#404. You have to make an emergency ditch at sea. The QNH of a nearby island airfield is 1025mb, airfield elevation 4000ft. The temp is -20°C. With 1025 set on your sub-scale, on ditching the altimeter will read:
TEMP IS -20 WHICH IS -ISA
AERODROME IS 4000 FT ABOVE MSL
HENCE QFF IS GREATER THEN QNH
IF QFF> QNH
AND QNH IS 1025
QFF WILL HAVE A VALUE 1025 OR ABOVE AND AS PER PRESSURE LEVEL CHART
ALTIMETER WILL READ LESS THAN 0 FEET
#405. Which of the following will indicate medium level instability, possibly leading to thunderstorms?
Altocumulus castellanus is a “bubbly” form of normal altocumulus. The “towers” that form in altocumulus castellanus are like battlements on castles, hence the name. These clouds are significant because they often herald a change to showery, thundery weather and are a feature of summer weather in temperate latitudes.
Cumulonimbus clouds sometimes develop from altocumulus castellanus, when instability is present at medium levels of the Troposphere.
#406. Radiation fog extends to:
Radiation fog is caused by radiation of the earth’s heat at night, and the subsequent conductive cooling of the air in contact with the ground to below dew point.
If there is a light wind, then fog will form, in calm conditions the result will be the formation of dew. The fog is not usually more than a few hundred feet thick.
#407. What is reported as precipitation?
#408. At FL60 what pressure chart would you use?
850 hpa is 5000 feet
800 HPA WOULD BE 6000 feet
#409. On a descent through cloud cover at high level you notice a white, cloudy or opaque, rough powder like substance on the leading edge of the wing. This contamination is likely to be:
rime ice is formed WHEN SMALL supercooled drops spread over wings
happen under 0° Celsius flying through clouds
#410. In association with CB in temperate latitudes, at about what levels can hail be anticipated?
CB EXTENDS FROM LOWEST LEVEL TO FL 450, IN PRESENCE OF CB HAIL CAN BE EXPECTED
#411. Moderate Turbulence
#412. ATIS reports:
The automatic provision of current, routine information to arriving and departing aircraft throughout 24 hrs or a specified portion thereof
Voice-ATIS broadcasts normally contain the following information in the order listed:
- name of aerodrome;
- arrival and/or departure indicator;
- contract type, if communication is via D-ATIS;
- designator;
- time of observation, if appropriate;
- type of approach(es) to be expected;
- the runway(s) in use; status of arresting system constituting a potential hazard, if any;
- significant runway surface conditions and, if appropriate, braking action;
- holding delay, if appropriate;
- transition level, if applicable;
- other essential operational information;
- surface wind direction (in degrees magnetic) and speed, including significant variations and, if surface wind sensors related specifically to the sections of runway(s) in use are available and the information is required by operators, the indication of the runway and the section of the runway to which the information refers;
- visibility and, when applicable, RVR;
- present weather;
- cloud below 1 500 m (5 000 ft) or below the highest minimum sector altitude, whichever is greater; cumulonimbus; if the sky is obscured, vertical visibility when available;
- air temperature;
- dew point temperature;
- altimeter setting(s);
- any available information on significant meteorological phenomena in the approach and climb-out areas including wind shear, and information on recent weather of operational significance;
- trend forecast, when available; and
- specific ATIS instructions.
#413. +TSRA come from what sort of cloud?
MEANS HEAVY INTENSITY
– MEANS LIGHT
CB GIVES HEAVY INTENSITY TSRA (THUNDER SHOWER AND RAIN)
#414. Flying 2500 ft below core of jet, with temperature increasing in the Southern Hemisphere, where does the wind come from?
With your back to the upper wind, the cold air is to your left in the northern hemisphere and to your right in the southern hemisphere.”
jet streams are mostly from west to east
#415. Secondary depressions move
This secondary may deepen and form the next depression along the PF and equal the size of the primary. At this stage, the depressions tend to rotate around each other cyclonically
#416. What temperature and pressure conditions would be safest to ensure that your flight level clears all the obstacles by the greatest margin?
True altitude in High pressure or warm atmosphere is always more than cold/low ,
hence qnh more than 1013 and temp more than isa
“watch out below when you are low”
#418. As an active cold front passes, the altimeter of an a/c parked on the apron
As the cold air advances, it forces the warm air upwards causing the warm air to cool. The water vapour in the warm air mass, consequently, condenses, and clouds are created. The slope of the cold front boundary is steeper than that of the warm front, with a gradient of approximately one in fifty.
The unstable air just ahead of the cold front is, forced to rise vigorously. Causing pressure to reduce and altimeter reading increased
#419. Where does a TRS gain its energy from?
Hurricanes.
Hurricane is the name given to Tropical Revolving Storms in the Caribbean/Gulf of Mexico Area. Frequency of developed Hurricanes is average 3 per year. They occur from August to October, tracking westwards across the Atlantic near 10°N-15°N latitude and at 10-15 knots. Internal windspeeds can exceed 100 knots. They then cross the Bay of Mexico or turn right around the sub tropical high to track NW, N, NE up the USA East Coast. They are energised by the latent heat of condensation and are therefore more active over the sea. Each season they are named alphabetically in order of occurrence using alternate male/female first names.
#420. What is the height and temperature of Tropopause?
over the poles, the tropopause can be between 8 -10 km and over the equator 16 – 18 km
The lower it is, the warmer the temperature at the tropopause. The temperature at the tropopause can be as high as -40°C over the poles and as low as -80°C over the equator.
#421. What is the Easterly wave?
#423. What is in position A?
CLOSED PACKED ISOBARS MEAN LOW PRESSURE
#424. The Geostrophic Wind blows at your flight level in Northern Hemisphere, true altitude and indicated altitude remain constant, is the crosswind
true altitude and indicated altitude remains same hence no cross wind
AS PER BUY BALLOTS LAW
#425. What is the base of alto cumulus in summer?
#426. What is the general height of radiation fog?
Radiation fog is caused by radiation of the earth’s heat at night, and the subsequent conductive cooling of the air in contact with the ground to below dew point.
If there is a light wind, then fog will form, in calm conditions the result will be the formation of dew. The fog is not usually more than a few hundred feet thick.
#427. When a CC layer lies over a West European plane in summer, with a mean terrain height of 500 m above sea level, the average cloud base could be expected
#428. Which of the following cloud types can stretch across all three cloud levels (low, medium and high level)?
CB EXTENDS FROM LOWEST LEVEL TO FL 450, IN PRESENCE OF CB HAIL CAN BE EXPECTED
#429. Which of the following cloud types can stretch across at least two cloud levels?
#430. Shortly after the passage of an active cold front you observe the aneroid altimeter of a parked aircraft. The indication of the instrument will
#431. In a shallow pressure distribution (widely spaced Isobars or low pressure gradients) you observe the aneroid altimeter of a parked aircraft for 10 minutes (no thunderstorms observed). The reading of the instrument will…
THERE IS NO REASON FOR THE READING TO CHANGE IF THERE WAS NO PRESSURE CHANGE
#432. You are flying from Marseilles (QNH 1012 hPa. to Palma de Mallorca (QNH 1012 hPa. at FL100. You notice that the effective height above MSL (Radio Altitude) increases constantly. Hence…
Since both the places have same pressure it is obvious that we are flying to a warmer place
true altitude increases in warmer atmosphere
#433. You are flying from Marseilles (QNH 1026 hPa. to Palma de Mallorca (QNH 1026 hPa. at FL100. You notice that the effective height above MSL (Radio Altitude) decreases constantly. Hence…
If temperature is warmer than ISA
then TRUE > INDICATED
and if it’s colder than ISA
then TRUE < INDICATED.
#434. Flying at FL 135 above the sea, the Radio Altimeter indicates a true altitude of 13500 ft. The local QNH is 1019 hPa. Hence the crossed air mass is, on average,
If the QNH was 1013mb, you’d be at 13,500 feet when at FL135. if you increased the subscale setting to 1019 the indication would increase, but as per radio altimeter it remains 13500 , this means that air mass was cold as true altitude decreases in cold air
#435. Which air mass has the coldest temperature?
If the airmass is lying over a warm tropical ocean, the airmass is classified as Tropical Maritime (TM).
If the airmass lies over a cold continent in winter, the airmass is classified as Polar Continental (PC).
#436. What happens to an aircraft altimeter on the ground once a cold front has passed?
#437. What happens to an aircrafts altimeter on the ground at the approach of a cold front?
#438. Even pressure system, no CB – what would you notice the altimeter in an aircraft on the ground to do during a 10 min period
THERE IS NO REASON FOR THE READING TO CHANGE IF THERE WAS NO PRESSURE CHANGE
#439. What weather phenomenon is over Northern Italy?
Ebbr falls ahead of a warm front
this will be the weather ahead of a warm front
Ahead of a warm front
Surface W/V – Speed increasing, slight backing, usually southerly.
Temperature – Steady low.
Dew Point – Steady low.
Pressure – Steady fall.
Cloud – Increasing to 8/8, base lowering.
Initially cloud changes from Ci to Cs to As, then very close to the front Ns.
Precipitation – Light continuous from As becoming moderate continuous from Ns.
Visibility – Reducing to poor.
#440. You are flying in the Alps at the same level as the summits on a hot day. What does the altimeter read?
As a thumb rule
if it’s warmer than ISA
then TRUE > INDICATED
and if it’s colder than ISA
then TRUE < INDICATED.
altimeter shows indicated altitude
hence lower altitude than summit
#441. What cloud is between a warm and cold front?
The area lying between the two fronts is known, since it is covered by tropical air, as the warm sector.
In the warm sector.
Surface W/V – Steady, usually from the SW.
Temperature – Steady.
Dew Point – Steady.
Pressure – Steadily decreasing.
Cloud – Uniform 6/8 to 8/8, some large breaks may occur, base low, St, Sc.
In summer over land – fair weather cumulus
Precipitation – Light rain, drizzle Visibility – Poor.
#442. From which cloud do you get hail?
#443. When flying from south to north in the Southern Hemisphere, you cross over the Polar Front Jet. What happens to the temperature?
PFJ ARE LOCATED IN WARM AIR
#444. If you see Alto Castellanus what does it indicate?
Altocumulus castellanus is a “bubbly” form of normal altocumulus. The “towers” that form in altocumulus castellanus are like battlements on castles, hence the name. These clouds are significant because they often herald a change to showery, thundery weather and are a feature of summer weather in temperate latitudes.
Cumulonimbus clouds sometimes develop from altocumulus castellanus, when instability is present at medium levels of the Troposphere.
#445. To dissipate cloud
An inversion in the atmosphere is where temperature rises with an increase in height. This produces extreme stability and inhibits the formation of cloud
In a high pressure system, air descends at the centre. As the air descends it will be heated adiabatically and will be warmer than the air at a lower level adjacent to the surface. This is called a Subsidence Inversion.
#446. When would a SIGMET be issued for subsonic flights
#447. Which of these statements about icing is correct?
Glaze ice or clear ice is formed when LARGE supercooled drops spread over wings
rime ice is formed WHEN SMALL supercooled drops spread over wings
both happen under 0° Celsius flying through clouds
#448. You will get least amount of icing in which cloud?
#449. The core of a jet stream is located
across the jet core, there is very little horizontal temp difference. There is, however, a big horizontal pressure difference.
#450. Isolated TS in summer are because of
Heat, or airmass type (more common in summer time).
Also called isolated
are formed by thermal triggering
not by frontal uplift
#451. Trade winds are most prominent or strongest
The trade winds are air currents closer to Earth’s surface that blow from east to west near the equator over the ocean
#452. A layer of air can be
if dry air is disturbed it will return to is original position, in other words the air is stable, however, when saturated air is disturbed it will continue to rise and it is unstable.
#453. On a significant weather chart you notice a surface weather front with an arrow labelled with the no. 5 pointing outward perpendicular from the front. This would indicate
#454. With all other things being equal with a high and a low having constantly spaced circular isobars. Where is the wind the fastest?
if air is moving steadily around a high, then the centrifugal force acts with the Pressure Gradient Force (PGF), increasing the velocity of the wind.
#455. Blocking Anticyclones prevent the polar front from arriving over the UK and originate from?
Blocking anticyclones are warm anticyclones formed from an extensions of high pressure areas developed in the sub- tropical regions, may hold up or divert the normal west-east passage of polar front depressions and persist for several days. In order for the anticyclone to block the passage of polar fronts it must be at higher latitudes than its parent sub tropical high. the blocking anticyclone must persist at latitudes between 45° to 65°
#456. Foehn winds are
The Föhn Wind is a warm dry wind which blows on the downwind side of a mountain range. It is a local wind in the Alps
#457. The Gust Front is
#458. Cu is an indication of
Cumulus cloud is the most common form of convective cloud, being classified as heaped cloud, from Latin cumulare meaning to heap up. For glider pilots, a developing cumulus is regarded as a reliable indication of the presence of thermal upcurrents
developed cumulus cloud is generally dense, with sharp outlines. As it continues to develop vertically, a cumulus cloud forms mounds, domes or towers, of which the upper parts often resemble the head of a cauliflower
#459. Which clouds are evidence of stable air?
Stratus (from Latin stratum, meaning strewn) is generally a grey, layered cloud with a fairly uniform base, which may produce drizzle, or light snow. Stratus cloud is no more than 1,000 – 1 500 ft thick, and is often much thinner
#460. Lack of cloud at low level in a stationary high is due to:
Clouds form with rising air, not sinking air, high pressure has air sinking in the centre
#461. What is the ratio of height to width in a typical Jet stream:
The length, width and height of a typical mid-latitude jet stream is 1000 nautical miles, 150 nautical miles and 18000 feet respectively. Depth width ratio of about 1:100
#462. When and where does an Easterly Jet stream occur:
TEJ tropical easterly jet stream
The easterly jet is a jet stream that occurs only in the summer of the northern hemisphere at approx. 45000 ft, from south east Asia extending over southern India to central Africa.
only one which travels to west
#463. What degree of turbulence, if any, is likely to be encountered while flying through a cold front in the summer over central Europe at FL100?
cb will be found at 10000 feet which will have severe turbulence
#464. An easterly wave is a:
#465. What is the most common freezing precipitation?
Freezing rain occurs when the layer of freezing air is so thin that the raindrops do not have enough time to freeze before reaching the ground. Hence precipitation is rain or drizzle,
#466. Which of the following is an example of a Foehn wind?
Although Föhn winds blow in the Alps, the name is used generically to describe winds which blow with similar effect in other parts of the world. One such wind is the Chinook which blows on the Eastern side of the Rocky mountains of North America.
#467. From which of the following clouds are you least likely to get precipitation in summer?
Cs are high level clouds and AS are medium level and are very less likely to produce rain , indicates approaching weather system
#468. What is a cold pool?
COLD AIR POOLS
These are outbreaks of cold air from near the poles. These outbreaks are usually characterized by a cold front at their leading edge. In fact they are common just behind the polar front depressions
Although surface temperature anomalies such as cold pools are not evident on surface pressure charts, they can be found most notably by looking at pressure charts in the middle to upper atmosphere. You may remember that cold air causes pressure to fall more rapidly with height, reducing the pressure in the upper atmosphere. Therefore by analyzing a pressure chart in the middle to upper atmosphere you can identify cold air pools by the low pressure they create
#469. Where do you find information on ICING and CAT?
ignificant Weather (SIGWX) charts provide invaluable meteorological information to aircraft operators and flight crew. Particularly for longer flights, or when weather issues may be a factor, SIGWX charts can be a vital flight planning tool.
the only cloud shown in waf sigwx chart is CB moderate and severe icing is associated to a cb, INFO ON CLEAR AIR TURBULENCE IS ALSO PROVIDED
#471. Relative humidity:
Relative Humidity is a term used to describe the quantity of water vapour that exists in a gaseous mixture of air and water.
water vapour increases rh changes
#472. What happens to the temperature of a saturated air mass when forced to descend?
Saturated air that is either forced to rise or descend within the atmosphere will change its temperature, on average by 0.6°C per 100 m (1.8°C/1000 ft).
The SALR varies strongly with the moisture content, which when saturated, depends on temperature, and pressure of the air parcel.
dalr temp will increase 1°C per 100 m , it will heat up more than salr
#473. A warm front occlusion is approaching the east coast of the UK. What WX would you expect in the North Sea during summer?
this is how an occluded front looks(cold or warm)
#474. What is the average height of the Tropopause at the equator?
The warmer the air, the higher the tropopause. The colder the air, the lower the tropopause. Generally over the poles, the tropopause can be between 8 -10 km and over the equator 16 – 18 km.
#475. The Tropopause is lower:
The warmer the air, the higher the tropopause. The colder the air, the lower the tropopause. Generally over the poles, the tropopause can be between 8 -10 km and over the equator 16 – 18 km.
#476. An airfield has an elevation of 540ft with a QNH of 993mb. An aircraft descends and lands at the airfield with 1013mb set. What will its altimeter read on landing?
1013 will be below 993 in atmosphere
20 hpa difference will add 540 feet
Under normal conditions, pressure varies by 1 hPa per 27 feet.
hence add 540 to current altitude
1080 feet with 1013 set
#477. In a METAR a gust is reported when:
mean speed taken over 10 minutes , gust reported 10 knots
#478. When is pressure altitude equal to true altitude?
True Altitude = Pressure Altitude plus(ISA Deviation × 4/1000 × Indicated Altitude)
if deviation is 0 true altitude is equal to pressure altitude
which is only in international standard condition
#479. What is the relationship between QFE and QNH at an airport 50ft below MSL?
In simple words
qfe is pressure at the airfield
qnh is pressure at the sea level right below the airport
setting QFE will give the height of the aircraft from the airfield
setting QNH will give height of the aircraft from the sea level( elevation)
if the airfield is below the sea level atmosphere will exert more pressure on the air field than sea level
#480. Where would a pilot find information about the presence of a jet stream?
Significant Weather (SIGWX) charts provide valuable meteorological information to aircraft operators and flight crew. Particularly for longer flights, or when weather issues may be a factor, SIGWX charts can be a vital flight planning tool.
the only cloud shown in waf sigwx chart is CB moderate and severe icing is associated to a cb AND INFORMATION ON JET STREAM AND CLEAR AIR TURBULENCE
#481. Up to FL180 ISA Deviation is ISA +10°C. What is the actual depth of the layer between FL60 and FL120?
FL120 minus FL060 is 6000 feet in ISA. The question relies upon you knowing the altimeter correction for temperature deviations from ISA. The accepted appoximation is 4% height difference for every 10°C below standard temperature as measured at the altimeter setting source. This is safe for all altimeter setting source altitudes for temperatures above -15°C.
6000 feet x0.04 x 10/10 = 240 feet
.The 0.04 is the 4%, the 10 is the ABOVE ISA deviation.
The altimeter will still register the difference as 6000 feet but in reality we have an approximate depth of 6240 feet
Warmer than ISA — altimeter under-reads.
Colder than ISA — altimeter over-reads.
#483. What is the effect of a mountain valley wind?
A wind blowing against a mountain is impeded. If the barrier is broken by a gap or valley, the wind will blow along the valley at an increased speed due to the restriction.
#484. What is the name of the dry, dusty wind blowing in North West Africa from the North East?
The Harmattan is a cool dusty wind that may reduce visibility to below 1000m, especially in areas bordering desert regions, such as Kano, Nigeria. The dust layer may extend to 7,000 or 10,000 ft or more, visibility improves towards the coast. The Harmattan blows from November through to April, though by this time the winds will be light, especially in the south.
#485. What is the difference between Gradient and Geostrophic winds?
The gradient wind occurs when the isobars are curved.
The Geostrophic Wind blows parallel to straight isobars.
#486. In still air a lapse rate of 1.2°C/100m refers to:
Elr is not a fixed value
where as
Saturated air lapse rate is0.6°C per 100 m (1.8°C/1000 ft).
unsaturated or dry air has lapse rate 1°C per 100 m (3°C/1000 ft)
#487. What happens to the temperature of a saturated air mass when descending
Saturated air that is either forced to rise or descend within the atmosphere will change its temperature, on average by 0.6°C per 100 m (1.8°C/1000 ft).
The SALR varies strongly with the moisture content, which when saturated, depends on temperature, and pressure of the air parcel.
dalr temp will increase 1°C per 100 m , it will heat up more than salr
#488. What prevents air from flowing directly from a high to a low pressure
Coriolis Force, (CF), is the force caused by the rotation of the earth.
It acts 90° to the wind direction causing air to turn to the right in the northern hemi-sphere and to the left in the Southern hemisphere. CF is maximum at the poles and minimum at the equator.
#490. Flying from A to B at a constant indicated altitude in the northern hemisphere.
when you fly from high to low altimeter overreads
also in a low Pressure area indicated altitude is more than true altitude hence true altitude is lower as indicated altitude is same.
#491. What is the relationship between the 5000 ft wind and the surface wind in the southern hemisphere
Due to friction the surface wind is slower than the geostrophic (freestream) wind.
In NH the surface wind Backs.
In SH the surface wind Veers
#492. What is the relationship between the 2000 ft wind and the surface wind in the Northern Hemisphere
Since surface friction has reduced the wind velocity, resulting in a reduction in the Coriolis Force, the PGF is now more dominating. This causes the wind to blow across the isobars towards the low
#493. The DALR is
Elr is not a fixed value
where as
Saturated air lapse rate is0.6°C per 100 m (1.8°C/1000 ft).
unsaturated or dry air has lapse rate 1°C per 100 m (3°C/1000 ft)