Water Cycle Flashcards
How much water on the planet is fresh water?
Less than 3% is freshwater.
How much fresh water is frozen in the cryosphere?
69%
How much fresh water is stored in the lithosphere?
30%
Define evaporation?
Evaporation occurs when liquid water changes state into a gas, becoming water vapour - it gains energy, normally from solar radiation. Evaporation increases the amount of water stored in the atmosphere.
Why does the magnitude of evaporation vary?
The magnitude of the evaporation flow varies by location and season. If there is lots of solar radiation, a large supply of water and warm, dry air, the amount of evaporation will be high.
If there is not much solar radiation, little available liquid water and cool air that is already nearly saturated (unable to absorb any more water vapour), evaporation will be low.
What is condensation?
Condensation occurs when water vapour changes state to become a liquid - it loses energy to the surrounding. It happens when air containing water vapour cools to its dew point (the temperature at which it will change from a gas to a liquid), e.g. when temperatures fall at night due to heat being lost to space.
Why does the magnitude of condensation flow vary?
The magnitude of the condensation flow depends on the amount of water vapour in the atmosphere and the temperature. For example, if there is lots of water vapour in the air and there’s a large or rapid drop in temperature condensation will be high.
How do clouds form?
Clouds form when warm air cools down, causing the water vapour in it to condense into water droplets, which gather as clouds. When the droplets get big enough, they fall as precipitation.
Describe frontal precipitation?
Warm air is less dense than cool air. As a result, when warm air meets cool air, the warm air is forced up above the cool air. It cools down as it rises this results in frontal precipitation.
Describe orographic precipitation?
When warm air meets mountains, its forced to rise, causing it to cool.
Describe convective precipitation?
When the sun heats up the ground, moisture on the ground evaporates and rises up in a column of warm air. As it gets higher, it cools. This results in convective precipitation.
Why does the magnitude of the cryosphere vary during periods of global cold?
During periods of global cold, inputs into the cryosphere are greater than outputs- water is transferred to us as snow, and less water is transferred away due to melting.
Why does the magnitude of the cryosphere vary during periods of warmer global temperatures?
During periods of warmer global temperatures, the magnitude of the cryosphere store reduces as losses due to melting are larger than the inputs of snow.
When was the last glacial period on Earth?
21,000 years ago.
