Atmosphere and weather 2.3

Question 1

Atmospheric moisture occurs in which three states?

Answer 1

Gas - water vapour, an invisible gas.
Liquid - water
Solid - ice

Question 2

What is the difference between absolute humidity and relative humidity?

Answer 2

• Absolute - the actual amount of water vapour in a given volume of air.
• Relative - compares the absolute humidity within the maximum amount that it could hold at that temperature and pressure.

Question 3

Causes of precipitation: convection

Answer 3

• Occurs over hot land where air is warmed by contact with the heat.
• The heated air expands, becomes less dense, rises and cools.
• Clouds forms as moisture in the air condenses and forms cumulonimbus clouds at the tropopause.

Question 4

Causes of precipitation: frontal uplift

Answer 4

• Occurs where warm tropical air masses meet cold polar air masses along polar fronts in mid latitudes.
• The less dense, warm air is pushed up over the cold air at the front.

Question 5

Causes of precipitation: orographic uplift

Answer 5

• When the pressure force is strong enough to cause air to rise over a hill or mountain.
• As it rises, it cools and reaches dew point temperature at condensation level where precipitation occurs on the rain slope.
• Descending air is compressed and warmed causing a rain shadow on other side of hill or mountain.

Question 6

What is radiation cooling?

Answer 6

Radiation cooling occurs when air near the ground is cooled by the Earth’s surface losing heat by radiation.

Question 7

Types of precipitation: fog

Answer 7

Tiny water droplets suspended in the air near the ground which reduces visibility.

Question 8

Types of precipitation: dew

Answer 8

Small droplets of water on leaves and grass etc.

Question 9

Types of precipitation: clouds

Answer 9

Suspensions of tiny water droplets which are too light to fall.

Question 10

Types of precipitation: rain

Answer 10

Larger water droplets which form when falling droplets collide and coalesce.

Question 11

Types of precipitation: snow

Answer 11

Aggregation of ice crystals arranged in hexagonal patterns

Question 12

Types of precipitation: hailstones

Answer 12

Formed when ice particles fall and rise in cumulonimbus clouds and water droplets collide and freeze around them (accretion).

Question 13

What are the three types of cloud?

Answer 13

• Stratus
• Cumulus
• Cirrus