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.

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.

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

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.

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.

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.

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.

difference between qfe and qnh is elevation

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

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.

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.

refer and remember this chart

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

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

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.

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

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

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.

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.

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.

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

rime ice is formed WHEN SMALL supercooled drops quickly spread over wings

happens under 0° Celsius flying through clouds

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.

The coldest air mass behind and the less cold air in front of the occlusion; the warm air mass is above ground level

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.

This diagram shows a warm occlusion,

tropical maritime are warm and moist

hence b is warm

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.

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

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.

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.)

at position b the winds are westerly which is just in front of the cold front, blue triangles  are cold font

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.

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.

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°

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.

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.

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.

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.

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.

dakar and itcz are at same place in summer

this is summer itcz North Africa

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.

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.

it is a polar front depression, which is moving from west to east

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

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

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

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.)

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

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.

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

London latitude is 51°

New York latitude is 40 °

position of itcz

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.

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

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°

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

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.

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

High pressure area are related to bad visibility and good weather,

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

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.

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

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.

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

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

Ridge is a high pressure area

in a high pressure are the wind subsides down and diverge

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.

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°

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.

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

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.

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

R16 means runway 16

P means plus

it means rvr for runway 16 is more than 1300 metre

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 0.3^oC would be coded as “00“. Sub-zero temperatures and dew points shall be prefixed with an M. For example, a temperature of 4^oC with a dew point of -2^oC would be coded as “04/M02“; a temperature of -0.5^oC would be coded as “M00“.

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.

Refer the chart

850 hpa is 5000 pressure altitude or fl50

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

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.

an additional 8 figure runway state code will be specified on the metar if there is any contamination

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

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

Decreasing the speed will give more allowance for the thrust and we can climb faster

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

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

.

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”

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

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.

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.

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.

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.

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.

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).

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

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

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

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

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

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

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.

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.”

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

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

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.