Water and carbon cycle 2 - The water cycle Flashcards
How much water does the hydrosphere contain
1.4 sextillion litres
What kind of water is this
Most is saline in the oceans
How much is freshwater
less than 3%
How much of the earths freshwater is frozen in the cryosphere?
69%
How much of the earths freshwater is in the groundwater?
30%
What does groundwater mean
Water stored underground in the lithosphere
How much of the earths freshwater is liquid freshwater?
0.3%
What is liquid freshwater
freshwater on the earths surface in lakes and rivers
How much of the earths freshwater is stored as water vapour in the atmosphere?
0.04%
What must water be
Pgtsically and economically accessible for humans to use
What is the problem with groundwater?
Its hard to accsess so not as cost effective as a result only a small percentage can be used by humans
What forms does water change in
Solid, liquid and gas
What happens when waters boils or melts
It has to gain energy from the sun
What happens when water condenses or freezes
It loses energy
What happens to water on a global scale
It is continuously cycled between different stores
What is this known as
Global hydrological cycle
What kind of cycle is this
closed
Why is it closed
There are no inputs or outputs of water. Energy in imputed from the sun and lost to space
What does the amount of water depend on
Dependent on whether it is a local or global scale
What does the magnitude of each store depend on
The amount of water flowing between them
Where do different flows occur
At a range of spatial and temporal scales
When does evaporation occur
When liquid changes to a gas
What is this gas called
water vapour
How does the liquid change to a gas
It gains energy from solar radiation
What does evaporation do
Increases the amount of water stored in the atmosphere
What does the magnitude of the evaporation flow vary with
Location and season
What happens if there is a lot of solar radiation
A large supply of water and warm dry air the amount of evaporation is high
What happens if there isn’t much solar radiation
Little available liquid water and cool air that is nearly saturated evaporation will be low
What does saturated mean
How ut is able to absorb water vapour
When does condensation occur
Water vapour changes state to become a liquid - it loses energy to its surroundings
When does it happen
When air containing water vapour cools to its drew point
What is drew point
The temperature when it changes from gas to liquid
What happens to the water droplets
They stay in the atmosphere or flow to other sub systems
What does the magnitude of condensation flow depend on
The amount of water vapour in the atmosphere and the temperature
What are 2 essential parts of the water cycle
Cloud formation and precipitation
What is the importance of precipitation
It’s the main flow of water from the atmosphere to the ground
When do 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 are big enough they fall as precipitation
What 3 things cause warm air to cool
- Other air masses
- Topography
- Convection
How do other air masses influence 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
What does this result in
Frontal precipitation
How does topography influence precipitation
When warm air meets mountains it is forced to rise causing it to cool
What does this result in
Orographic precipitation
How does convection influence 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
What does this result in
Convective precipitation
Why can’t water droplets caused by condensation form clouds
They are too small
What has to be present for clouds to form
Tiny particles of other substances (like dust) to act as a cloud condensation nuclei
What does a cloud condensation nuclei do
They give water a surface to condense on
Why is this important
It encourages clouds to form, rather than allowing moist air to disperse
What are 2 examples of cryospheric processes
Accumulation and ablation
How does cloud formation and precipitation vary
Seasonally and by location
What do cryospheric processes do
Change the amount of water stored as ice in the cry-sphere
What does the balance of accumulation and ablation vary with
Temnperature
What happens in periods of global cold
Inputs into the cryosphere are greater than the outputs - water is transferred as snow snd less ware is transferred away due to melting
What happens in periods of global warmth.
The magnitude of the cry-sphere store reduces as losses due to melting are larger than inputs of snow
What is happening to the earth
It;’s emerging from a glacial period that reached its maximum 21,000 years ago
Where are the extensive stores of ice
Antartica, Greenland and a number of alpine glaciers
How do variations in cryospheric processes happen
Over different time scales
What is an example of a short time scale variation
Annual temperature fluctuations mean that snow falls more in winter than summer
