The water cycle on a global scale Flashcards
What is the largest store in the global water cycle?
Oceans, containing 97% of global water.
What percentage of global water is freshwater?
Only 2.5%
What proportion d freshwater is stored in glaciers, ice caps, and ice sheets?
69%
What percentage of freshwater is groundwater?
30%
What accounts for only 1% of global freshwater stores?
Surface and other freshwater
What makes up surface and other freshwater?
Permafrost, lakes, swamps, marshes, rivers, and living organisms
What are the four areas where water can be stored?
Hydrosphere - Any liquid water
Lithosphere - Water stored in the crust and upper mantle
Cryosphere - Any water that is frozen
Atmosphere - Water vapour
What are aquifers?
Underground water stores that are unevenly distributed globally
How long can shallow groundwater aquifers store water?
Up to 200 years
How long can deeper fossil aquifers store water?
Up to 10,000 years, formed during wetter climatic periods.
How long do glaciers store water?
20-100 years, feeding lakes that store water for 50-100 years.
How long does seasonal snow cover and rivers store water?
2-6 months
How long does soil water act as a temporary store?
1-2 months
What is the ITCZ?
The Inter-Tropical Convergence Zone, a low-pressure zone at the equator with heavy rainfall.
What causes precipitation in the ITCZ?
Convectional rainfall from rising and falling air in the global atmospheric circulation model.
