What are the climatic distribution characteristics of tropical deserts in South America? What is the reason?

The annual average temperature is high, the annual temperature difference is large, the daily temperature difference is large, and precipitation is scarce. The annual precipitation is generally below 250 mm, and in many areas it is only tens or even several millimeters. Precipitation varies greatly, and it often doesn't rain for several years.

Second, the reason:

1, controlled by the subtropical high belt.

Subtropical high is a kind of dynamic high, which is a warm high because the air flow over the equator continuously accumulates over the subtropical zone, resulting in downward air flow, which leads to the increase of low-altitude air pressure. The subtropical weather is sunny and dry, mainly because of the prevailing downdraft.

2, controlled by dry trade winds

Trade winds are directional winds blowing from subtropical high to equatorial low. The earth's rotation and wind deflection turn left in the southern hemisphere, becoming a southeast wind. In the subtropical region of the southern hemisphere, the west coast of the mainland is on the leeward side of the southeast trade wind, and the east coast of the mainland is on the windward side of the southeast trade wind. It makes the precipitation on the west coast of the mainland in the subtropical region of the northern and southern hemispheres scarce, the climate is dry and there are deserts.

3. Affected by cold current

Ocean currents have a great influence on the climate. Cold current can reduce the temperature and humidity of the area it flows through, while warm current can increase the temperature and humidity of the area it flows through. In subtropical areas, the west coast of the mainland is affected by the cold current, with scarce precipitation and dry climate; The east coast of the mainland is affected by the warm current, and there is more precipitation.

Extended data:

Influence of tropical desert climate on this area

1, less precipitation, large variability: little precipitation. Iquiji, also located in the desert of northern Chile, had no rain for four consecutive years, but in the fifth year, a shower dropped by 65,438+05 mm, and in the second year, a shower record reached 63.5 mm, showing great variability. Rainfall in tropical deserts is mostly explosive showers, which often cause serious soil erosion.

2. High temperature and large temperature difference: Due to less clouds, strong sunshine, insufficient vegetation coverage and low air humidity, the temperature rises extremely rapidly during the day. It is recorded that the temperature in North Africa is as high as 58℃. Generally, the average monthly temperature in summer is between 30℃ and 35℃, and the high temperature lasts for a long time. For example, in Aden, Arabian Peninsula, the monthly average temperature is above 30℃ for five months in a year.

3. Strong evaporation and low relative humidity: The tropical desert climate has strong evaporation because it is often cloudless, windy, sunny, high temperature and low relative humidity in Wan Li. The possible evapotranspiration is 20 times or even about 100 times of precipitation.

Baidu Encyclopedia-Tropical Desert Climate