Atmospheric moisture and precipitation

Question 1

Why do we need the hydrological cycle?

Answer 1

To manage the constant great inputs and outputs of water to sustain global climate

Question 2

How does evaporation transport heat?

Answer 2

Through latent heat

Question 3

When can more water be held in the air?

Answer 3

At higher temperatures

Question 4

What is absolute humidity?

Answer 4

Mass of water held by particular volume of air

Question 5

What is relative humidity %?

Answer 5

Ratio of aired actual vapour to the maximum it could hold at that temperature

Question 6

What happens to air parcels when the rise and sink?

Answer 6

When they rise the surrounding pressure decreases (parcel has higher pressure) so it expands, does work and cools (decreases adiabatically)
Parcel contracts when sinking and warms (goes to area go high pressure)

Question 7

What is an adiabatic process?

Answer 7

No energy is added or taken away from system

Question 8

What does a parcel of air cool at if it hasn’t reached saturation?

Answer 8

Dry adiabatic lapse rate

Question 9

What is lapse rate?

Answer 9

Way temperature changes with height of atmosphere

Question 10

What is saturated adiabatic lapse rate?

Answer 10

When parcel of air is saturated latent heat is released, slowing rate of cooling

Question 11

What is needed for latent heat of melting/ vaporisation?

Answer 11

Energy must be applied to break the bonds

Question 12

What happens to energy during sublimation, condensation and freezing?

Answer 12

Energy returned to atmosphere as sensible heat (warms up surroundings)

Question 13

What are the different atmospheric stabilitys?

Answer 13

Unstable - air parcel warmer than surroundings (rise)
Neutral - air parcel same temp as surroundings (remain)
Stable - air parcel cooler (move down)

Question 14

What is the lifting condensation level?

Answer 14

Level at which a parcel of moist air lifted dry adiabatically becomes saturated

Question 15

What 4 ways is air lifted?

Answer 15

• Orographic lifting (over mountain)
• Frontal uplift (warm over cold air mass)
• Convectional lifting (heating of warm surface)
• Convergence and uplift

Question 16

How is fog formed?

Answer 16

• Warm mass of air passes over cold land, lowest layers may be cooled to dew point creating fog
• Cold air moves over warm sea (advection fog)

Question 17

How it radiation fog formed?

Answer 17

Calm clear nights, land cool lowest layers to below dew point, once fog forms upper layer of fog radiates heat away thickening the fog

Question 18

How does Vally fog form?

Answer 18

Downslope movement of cold air (dense), if air is moist enough and cools below dew point

Question 19

How does a cloud drop become a rain drop?

Answer 19

• cloud drop needs to be heavy enough to fall and not be held up by currents
• must not evaporate before ground
• for snow crystals must not melt

Question 20

What is needed to form precipitation?

Answer 20

• Saturated air
• Lifting mechanism
• Condensation nuclei

Question 21

What is the collision-coalescence process?

Answer 21

• Takes place in warm clouds
• Bigger drops fall faster and overtaken and absorbs smaller drops
• Small drops swept aside

Question 22

What is the Bergeron-Findeisen process?

Answer 22

• Occurs in mixed ice-water clouds
• Iice crystals form on ice nuclei
• Water vapour moves towards ice crystals and makes them bigger

Question 23

What are the 2 process which droplets form?

Answer 23

Bergeron-Findeisen proces
collision-coalescence process

Question 24

What are the 3 cloud types?

Answer 24

Stratus clouds - sheet like (pure status clouds below 2000m)
Cumulus clouds - individual clouds with visible outline (vertical growth)
Cirrus clouds - short detached hair like clouds at high altitudes (above 6000m)

Question 25

What is an alto stratus cloud?

Answer 25

Mid level sheet like

Question 26

What is a nimbostratus cloud?

Answer 26

Mid level sheet like, associated with rain

Question 27

What is a cumulonimbus cloud?

Answer 27

verticle cloud associated with rain, lower than 200m