What are the main factors affecting precipitation?
2. Atmosphere: It mainly includes the influence of atmospheric circulation, front, cyclone and anticyclone on precipitation.
(1) Atmospheric circulation includes three-cycle circulation and monsoon circulation. Three circulations form seven pressure zones and six wind zones, in which the low pressure zone controls more precipitation, while the high pressure is the opposite; There is more precipitation on the west coast than on the east coast in the westerlies, and more precipitation on the east coast than on the west coast in the trade winds. In the monsoon circulation, summer monsoon precipitation is more than winter monsoon.
(2) Fronts: Cold fronts, warm fronts and quasi-static fronts are prone to precipitation when crossing the border.
(3) Cyclones correspond to low pressure, and it is rainy when the airflow rises; The anticyclone corresponds to high pressure, and the sinking of airflow is sunny.
3. 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.
4. Ocean current: Warm current can warm and wet coastal climate; 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.
5. 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.
6. Human activities: the urban wet island effect is that many updrafts in the city are easy to form clouds and cause rainfall; The rain island effect is that the city has more dust, more condensation nuclei, more fog and low clouds than the effective area.
Extended data:
The main process of precipitation is:
1. With the development of weather system, warm and humid air streams meet with cold air, which causes the warm and humid air streams to be forcibly lifted by cold air or climb from the warm and humid air streams along the front slope.
2. Local thermal convection in summer makes warm and humid air rise with strong convection, forming small cumulonimbus clouds and thunderstorms.
3. The ups and downs of the terrain make 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.
Precipitation conditions:
1, is to have enough water vapor;
2. It is to make the air block rise and cool and condense;
3. More condensation nuclei are needed.
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