HUMIDITY – Air – DGCA Question Bank For Politics

#1. Relative humidity depends on

moisture content of the air only

temperature of the air only

moisture content and temperature of the air

moisture content and pressure of the air

#2. When a given mass of air descends, what effect will it have on relative humidity?

It increases.

It remains constant.

It increases up to 100%, and then remains stable

It decreases.

#3. What does dewpoint mean?

The freezing level (danger of icing).

The temperature at which the relative humidity and saturation vapour pressure are the same.

The temperature to which a mass of air must be cooled in order to reach saturation.

The temperature at which ice melts.

#4. Relative humidity at a given temperature is the relation between:

water vapour weight and humid air volume

dew point and air temperature

actual water vapour content and saturated water vapour content

water vapour weight and dry air weight

#5. The maximum amount of water vapour that the air can contain depends on the:

air temperature

relative humidity

stability of the air

dewpoint

#6. Which of the following changes of state is known as sublimation?

Solid direct to liquid

Liquid direct to solid

Liquid direct to vapour

Solid direct to vapour

#7. When water evaporates into unsaturated air:

heat is absorbed

heat is released

relative humidity is not changed

relative humidity is decreased

#8. Which of the following statements is true of the dew point of an air mass?

It can only be equal to, or lower, than the temperature of the air mass

It can be higher than the temperature of the air mass

It can be used together with the air pressure to estimate the air mass’s relative humidity

It can be used to estimate the air mass’s relative humidity even if the air temperature is unknown

#9. The process by which water vapour is transformed directly into ice is known as:

sublimation

supercooling

supersaturation

radiation cooling

#10. During the late afternoon an air temperature of +12°C and a dew point of +5°C were measured. What temperature change must occur during the night in order to induce saturation?

It must decrease to +7°C.

It must decrease to +5°C.

It must decrease by 5°C.

It must decrease to +6°C.

#11. Dew point is defined as:

the temperature below which the change of state in a given volume of air will result in the absorption of latent heat

the temperature to which moist air must be cooled to become saturated at a given pressure

the lowest temperature at which evaporation will occur for a given pressure

the lowest temperature to which air must be cooled in order to reduce the relative humidity

#12. How, if at all, is the relative humidity of an unsaturated air mass influenced by temperature changes?

It increases with increasing temperature.

It is only influenced by the amount of water vapour.

It decreases with increasing temperature.

It is not influenced by temperature changes

#13. Relative humidity:

increases if the air is cooled whilst maintaining the vapour pressure constant

is higher in warm air than in cool air

is higher in cool air than in warm air

decreases if the air is cooled whilst maintaining the vapour pressure constant

#14. In which of the following changes of state is latent heat released?

Gas to liquid

Solid to liquid

Solid to gas

Liquid to gas

#15. The dewpoint temperature:

can be reached by cooling the air whilst keeping pressure constant

can be reached by lowering the pressure whilst keeping temperature constant

can not be equal to the air temperature

can not be lower than the air temperature

#16. Which of the following is the definition of relative humidity?

Ratio between water vapour pressure and atmospheric pressure X 100

Ratio between water vapour (g) and air (kg) X 100

Ratio between the actual mixing ratio and the saturation mixing ratio X 100

Ratio between air temperature and dewpoint temperature X100

#17. The difference between temperature and dewpoint is greater in:

moist air

air with high temperature

air with low temperature

dry air

#18. A parcel of moist but not saturated air rises due to adiabatic effects. Which of the following changes?

Mixing ratio

Specific humidity

Relative humidity

Absolute humidity

#19. Relative humidity:

does not change when water vapour is added provided the temperature of the air remains constant

changes when water vapour is added, even though the temperature remains constant.

is not affected when air is ascending or descending.

is not affected by temperature changes of the air

#20. The relative humidity of a sample air mass is 50%. How is the relative humidity of this air mass influenced by changes of the amount of water vapour in it?

It decreases with increasing water vapour

It is only influenced by temperature.

It increases with increasing water vapour

It is not influenced by changing water vapour

#21. How does relative humidity and the dewpoint in an unsaturated air mass change with varying temperature?

When temperature increases, the relative humidity decreases, and the dewpoint remains constant.

When temperature increases, the relative humidity increases, and the dewpoint decreases.

When temperature decreases, the relative humidity decreases, and the dewpoint increases

When temperature decreases, the relative humidity and the dewpoint remain constant.

#22. In which layer is most of the atmospheric humidity concentrated?

Stratosphere.

Stratopause.

Troposphere.

Tropopause.

#23. The dewpoint temperature