Results
#1. What is the relationship between meteorological visibility and RVR in homogeneous fog?
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.
#2. Visibility is reduced by haze when:
Haze. There is haze if the visibility is reduced by extremely small solid particles – sand, dust or smoke. If the visibility is reduced below 1000m. Again, haze is not reported when the visibility is more than 5000m.
Poor visibility is usually associated with stable conditions, an inversion and light winds.
#3. 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.
#4. When is the RVR reported at most airports?
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.
#6. Which of the following conditions is most likely to lead to the formation of advection fog ?
#8. Flight visibility from the cockpit during approach in a tropical downpour can decrease to minimal:
#9. The most likely reason for radiation fog to dissipate or become low stratus is:
By insolation causing convection which will lift the fog. It will also help to evaporate the lower layers.
By a strong wind lifting the fog to form stratus cloud.
#10. Advection fog can be formed when:
#11. Below a low level inversion visibility is often:
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
#12. Which of the following conditions is most likely to lead to the formation of steam fog (arctic smoke)?
#15. Which of the following statements is true concerning advection fog?
can form in day or night
#16. What wind conditions, occurring just before dawn, favour the formation of fog at an airport where the temperature is 15°C and the dew point is 14°C?
The dew point is the temperature the air needs to be cooled to (at constant pressure) in order to achieve a relative humidity (RH) of 100%
if dew point is same as temperature
calm wind needs to prevail in order to form radiation fog
as all other conditions are met
#17. Advection is:
#19. At what time of day, or night, is radiation fog most likely to occur?
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.
#20. What conditions are most likely to lead to the formation of hill fog?
#22. What are the differences between radiation fog and advection fog ?
#23. Frontal fog is most likely to occur:
Frontal fog occurs at a warm front or occlusion. The main cause is precipitation lowering the cloud base to the ground.
#24. While approaching your target aerodrome you receive the following message: RVR runway 23: 400m. This information indicates the:
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.
#25. Which of the following is most likely to lead to the formation of radiation fog?
#27. In general, the meteorological visibility during rainfall compared to during drizzle is:
#28. Which type of fog is likely to form when air having temperature of 15°C and dew point of 12°C blows at 10 knots over a sea surface having temperatures of 5°C?
#29. Steaming fog (arctic sea smoke) occurs in air:
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.
#31. In the vicinity of industrial areas, smoke is most likely to affect surface visibility when:
- 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.
#32. A significant inversion at low height is a characteristic of:
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
- 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.
#33. In unstable air, surface visibility is most likely to be restricted by:
Unstable air means low pressure in low pressure low visibility can be due to precipitation and not fog,
#34. When the temperature and dew point are less than one degree apart the weather conditions are most likely to be:
Closer the temperature and dew point , saturation occurs and fog formation is likely