The Atmosphere

Question 1

Difference between absolute and relative humidity?

Answer 1

Absolute humidity is the quantity of water in the air in grams per cubic meter.

Relative humidity is absolute humidity in relation to the quantity required for air to be saturated, expressed as a percentage.

Question 2

What is Dew Point?

Answer 2

Temperature at which a parcel of air is saturated and has a relative humidity of 100%.

Question 3

What happens if we cool air below its dew point?

Answer 3

Water vapor contained within the air mass will begin to condense out.

Question 4

What are three causes of saturation?

Answer 4

• Cooling
• Mixing
• Evaporation

Question 5

What is the adiabatic process?

Answer 5

A parcel of air changes temperature due to expansion or compression without heat energy being added or removed from the parcel from external sources.

Question 6

What happens to an air parcel as it rises/falls?

Answer 6

• Rises: Cools down due to expansion.
• Falls: Warms due to compression.

Question 7

What are the four lifting mechanisms at which a parcel of air rises?

Answer 7

• Convection
• Convergence
• Orographic
• Frontal

Question 8

When a cold and warm air masses meet, which one is lifted?

Answer 8

When a cold and warm air masses meet, the warmer is lifted up by the cooler one.

Question 9

How does the UK’s Met Office classify clouds? And what clouds are included within each classification?

Answer 9

Three layers:

• Low Clouds: Bellow 6,500ft (2000m). Stratocumulus, stratus, cumulus, cumulonimbus.
• Medium Clouds: 6,500ft to 20,000ft (2,000m to 6,000m). Altocumulus, Altostratus, Nimbostratus.
• High Clouds: More than 20,000ft (6,000m). Cirrus, Cirrocumulus, Cirrostratus.