5.1 Flashcards
What is a closed system?
When there is a transfer of energy but not matter between the system and its surroundings.
There are no external inputs/outputs - any come from within the system.
What is a flow (flux)?
Measurements of the rate of flow between stores.
What are processes?
The physical mechanisms, such a evaporation, that drive the flows of water between stores
What is a store?
A reservoir where water is held e.g. oceans
What is blue water?
Water that is stored in rivers, streams, lakes and groundwater in liquid form (visible)
What is green water?
Water stored in the soil and vegetation
How does precipitation reach land?
- High flux in oceans uptake water through evaporation.
- Wind blows clouds over land
- The transported water falls upon land
- The precipitation levels are higher than the evaporation levels on the land, albeit with a much smaller flux
What is the water budget?
The total volume of water that has fallen as precipitation added to the volume of water that has evaporated.
Compare ocean flux and atmosphere flux times (size of water store, residency time)
Ocean flux times much larger, as more water is evaporated/precipitated, as it is a larger store.
This is why residency time in the ocean is much larger, averaging 3600 years, compared to the residency time in the atmosphere, which averages 10 days
Why is there a lack of availability to fresh water?
- Water in oceans contain saline
- Largest store of fresh water is glaciers and icecaps, which can’t be accessed (residence time of 1000-10000 years)
- Precipitation falling onto the cryosphere has a residence time of 15000 years - very slowly produced
- Increase in population —> increase in demand and consumption, further limiting availability
How does climate change affect the freshwater
budget?
The increase in global temperature causes glaciers to melt faster. As a result, meaning freshwater stores aren’t being replenished fast enough.
What type of system is the global hydrological cycle?
It is a closed system
