Main factors affecting precipitation

Location: mainly the influence of land and sea location on precipitation. Usually the mainland is dry and there is little rain. Atmosphere: It mainly includes the influence of atmospheric circulation, front, cyclone and anticyclone on precipitation. Terrain: there is more precipitation on windward slope and less precipitation on leeward slope; High terrain will also prevent water vapor from entering. For example, the reason for the dry climate in Xinjiang is not only the inland depths, but also the blocking of water vapor by the surrounding mountains.

Ocean current: Warm current flows through the coastal climate, increasing temperature and humidity; The cold current flowing through the coastal climate can reduce temperature and humidity. For example, the desert in Australia extends to the vast area on the west coast of the mainland, which is not only controlled by the subtropical high, but also affected by the trade winds and the cold current in Western Australia. For another example, the seaports of Britain and Norway benefit from the warm current of the North Atlantic because they are not frozen all year round.

Vegetation and hydrological conditions: in areas with high vegetation coverage and around lakes, swamps and reservoirs, the air humidity is relatively high and the relative precipitation is relatively high.

The main process of precipitation is:

① With the development of weather system, warm and humid air meets cold air, which makes the warm and humid air forced to rise or climb along the front slope by cold air.

② In summer, local thermal convection makes warm and humid air rise with strong convection, forming small cumulonimbus clouds and thunderstorms.

(3) Topographic fluctuation makes the windward slope rise forcibly, but this is a relatively minor factor. In most cases, it is combined with the first two processes and affects the geographical distribution of precipitation.