DGCA Meteorology: Humidity Questions
44 exam-style Humidity questions for the DGCA Meteorologypaper (CPL & ATPL). The first 12 are free below with answers and explanations — sign up free to practise all of them with progress tracking.
- Q1
The difference between air temperature and dew point temperature is greater in:
- AMoist air
- BDry air
- CSaturated air
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Correct answer: B. Dry air
Dry air has a bigger gap between temp and dew point since it’s far from saturation.
- Q2
Relative humidity depends on
- Amoisture content and pressure of the air
- Btemperature of the air only
- Cmoisture content and temperature of the air
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Correct answer: C. moisture content and temperature of the air
Relative humidity is the ratio of the actual water-vapour content to the maximum the air can hold, and that capacity is set by temperature, so RH depends on both the moisture content and the temperature of the air.
- Q3
Humidity mixing ratio during adiabatic ascent:
- AIncreases
- BRemains constant
- CDecreases
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Correct answer: B. Remains constant
No moisture is added or lost in adiabatic ascent, so the mixing ratio stays put.
- Q4
If the spread between temperature and dew point is least, the air is:
- ADry
- BSaturated or near saturation
- CUnstable
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Correct answer: B. Saturated or near saturation
A small temp-dew point gap means the air is almost fully humid.
- Q5
Humidity mixing Ratio _____ when air is lifted adiabatically
- Adecreases
- Bincreases
- Cremains constant
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Correct answer: C. remains constant
The humidity mixing ratio stays constant during adiabatic lifting of unsaturated air, since no water vapour is added or removed; it only begins to fall once the air saturates and condensation removes vapour.
- Q6
Humidity mixing Ratio _____ when air is lifted adiabatically
- Aremains constant
- Bdecreases
- Cincreases
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Correct answer: A. remains constant
During adiabatic ascent of unsaturated air the humidity mixing ratio remains constant, because the mass of water vapour per kilogram of dry air is unchanged until condensation begins.
- Q7
Dependence of water vapor content on air temperature.
- ADecreases as temperature increases
- BIncreases as temperature increases
- CRemains constant regardless of temperature
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Correct answer: B. Increases as temperature increases
The water-vapour capacity of air increases as temperature increases, roughly doubling for every 10 degree C rise, which is why warm tropical air can hold far more moisture than cold polar air.
- Q8
Relative humidity depends on
- Amoisture content of the air only
- Btemperature of the air only
- Cmoisture content and temperature of the air
- Dmoisture content and pressure of the air
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Correct answer: C. moisture content and temperature of the air
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- Q9
When a given mass of air descends, what effect will it have on relative humidity?
- AIt increases.
- BIt remains constant.
- CIt increases up to 100%, and then remains stable
- DIt decreases.
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Correct answer: D. It decreases.
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- Q10
What does dewpoint mean?
- AThe freezing level (danger of icing).
- BThe temperature at which the relative humidity and saturation vapour pressure are the same.
- CThe temperature to which a mass of air must be cooled in order to reach saturation.
- DThe temperature at which ice melts.
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Correct answer: C. The temperature to which a mass of air must be cooled in order to reach saturation.
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- Q11
Relative humidity at a given temperature is the relation between:
- Awater vapour weight and humid air volume
- Bdew point and air temperature
- Cactual water vapour content and saturated water vapour content
- Dwater vapour weight and dry air weight
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Correct answer: C. actual water vapour content and saturated water vapour content
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- Q12
The maximum amount of water vapour that the air can contain depends on the:
- Aair temperature
- Brelative humidity
- Cstability of the air
- Ddewpoint
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Correct answer: A. air temperature
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