Water Cycle

Question 1

How much of the water on Earth is freshwater?

Answer 1

3%

Question 2

What stores is the freshwater divided into?

Answer 2

69% in cryosphere
30% in groundwater
0.3% as liquid freshwater
0.04% as water vapour

Question 3

What is groundwater?

Answer 3

Water stored underground in lithosphere

Question 4

What is the global hydrological cycle?

Answer 4

Water constantly cycled between stores

Question 5

What type of system is the global hydrological cycle?

Answer 5

Closed - no input or output of water

Question 6

What does the magnitude of each store depend on?

Answer 6

Amount of water flowing through the store

Question 7

How does evaporation affect the water cycle?

Answer 7

Increases amount of water stored in atmosphere

Question 8

Why does the magnitude of evaporation vary by location and season?

Answer 8

• If there’s lots of solar radiation and a large supply of water + warm dry air, evaporation is high
• if there’s little solar radiation, small supply of water and cold damp air, evaporation will be low

Question 9

When does condensation occur?

Answer 9

When air containing water vapour cools to its dew point

Question 10

What is the dew point?

Answer 10

Temperature at which water vapour turns to liquid

Question 11

How does condensation affect the water cycle? Give an example.

Answer 11

Water droplets can stay in the atmosphere or flow to other subsystems e.g. condensation = dew on leaves = less water stored in atmosphere

Question 12

What is the magnitude of condensation dependent on? Give an example.

Answer 12

Amount of water vapour in the atmosphere
Temperature
e.g. lots of water vapour + drop in temp = high condensation

Question 13

What are 2 essentials of the water cycle?

Answer 13

Cloud formation

Precipitation

Question 14

Why is precipitation important in the water cycle?

Answer 14

It’s the main flow of water from atmosphere to ground

Question 15

How do clouds form?

Answer 15

When warm air cools, causing water vapour to condense and turn into water droplets, which gather as clouds.
When they’re big enough, they fall as precipitation.

Question 16

What 3 things affect cloud formation?

Answer 16

1. Other air masses
2. Topography
3. Convection

Question 17

How do ‘Other Air Masses’ affect cloud formation? What type of precipitation does this result in?

Answer 17

Warm air = less dense than cold air.
When warm air meets cold air, it’s forced above cool air, where it cools as it rises.
This results in frontal precipitation.

Question 18

How does topography affect cloud formation? What type of precipitation does this result in?

Answer 18

Warm air is forced to rise when it meets mountains, causing it to cool.
This results in orographic precipitation.

Question 19

How does convection affect cloud formation? What type of precipitation does this result in?

Answer 19

When sun heats ground, moisture on ground evaporates + rises.
It cools as it rises.
This results in convective precipitation?

Question 20

Why can’t clouds form from water droplets alone?

Answer 20

Water droplets are too small - for cloud formation there need to be other tiny particles of substances e.g. soot to act as cloud condensation nuclei.
This gives water a surface on which to condense on

Question 21

What 2 factors cause variation in cloud formation?

Answer 21

Season - in UK more rain in winter than summer

Location - Precipitation higher in tropic than poles

Question 22

How do cryospheric processes affect the water cycle?

Answer 22

Cryospheric processes change amount of water stored in cryosphere - varies with temperature

Question 23

How do periods of global cold affect water storage in the cryosphere?

Answer 23

Inputs>outputs
Input = snow
output = melting

Question 24

How do periods of global warming affect water storage in the cryosphere?

Answer 24

Inputs < outputs
Inputs = snow
outputs = melting

Question 25

How is water storage in the cryosphere affected over short timescales?

Answer 25

Annual temp fluctuations - more snow in winter than summer