- The average temperature across the world is 8.77 degrees but [the map] mainly shows the amount of evaporation which is occurring
- Climate and air strongly influence the output of evapotranspiration
- If evapotranspiration is higher than precipitation in an area, there will be a water budget deficit.
- Low precipitation means a water budget deficit is more likely
- Global climates are determined by temperature and precipitation
- Further from the equator = decrease in temperature and precipitation patterns which are much more complex
- The ITCZ (inter-tropical convergence zone) is what causes so much equatorial rainfall e.g Amazon Rainforest. Sinking air causes less precipitation. Mid latitude air rises again causing more precipitation e.g over the UK
Water Budgets, Climate &
Latitudes:
- When water from precipitation is greater than the amount of evapotranspiration, this means there is a surplus of water. When precipitation is less than evapotranspiration, there is a deficit.
- Very generally speaking the most precipitation is at the equator, then very little north and south in the desert regions, and then more again in temperate latitudes. The polar regions have low precipitation in general. These rules vary due to seasonality, proximity to the coasts, mountains effects.
- The tropics have the most rainfall in general as the sun is the strongest globally and this energy drives evapotranspiration over rainforests and a lot of convectional rainfall. Further north and south the air is drier and sinks; this creates deserts. Rainforests usually have water surpluses, deserts usually have deficits.
- The temperate regions have rising air, and a lot of frontal rainfall from interactions of tropical area with colder polar air (depressions or low pressure). Therefore, water surpluses result in the winter, but might become deficits in the summer (anti-cyclones and high pressure).
- In colder polar regions like the arctic and Antarctic, the air is very cold and dry (cold air cannot hold as much moisture) and precipitation is generally low. Antarctica is classed as a desert
River Regimes:
- Show the annual variation of discharge of a river
- They show the impact climate, geology and soils have in different river basins.