Why does downward flow cause hot weather?

Because the water vapor can't rise in the downward flow, it will inhibit the formation of clouds, which will cause the heat of the sun to reach the ground unimpeded and play a warming role. At the same time, because there is no cloud, it won't rain. So downward flow has a warming effect. Subtropical high and cyclone edge will have downdraft.

Clouds are made up of water vapor in the atmosphere. Generally distributed in the troposphere at the bottom of the atmosphere. The temperature in the troposphere is characterized by the higher the altitude, the lower the temperature, and the temperature drops by 6 degrees Celsius for every increase of 1000 meters. Conversely, the lower the height, the higher the temperature.

The airflow contains a lot of water vapor. When the downward flow moves to a lower position, the water vapor is evaporated due to the higher temperature, so the air flow becomes drier and the clouds naturally decrease.

Related introduction:

The standard of high temperature heat wave recommended by the World Meteorological Organization is that the daily maximum temperature is higher than 32℃ and lasts for more than 3 days. Meteorology in China generally refers to the high temperature when the maximum daily temperature reaches or exceeds 35℃.

Hot weather will make people feel uncomfortable, reduce work efficiency and increase the incidence of heatstroke, intestinal diseases and cardiovascular and cerebrovascular diseases. At the same time, high temperature weather will also have a greater impact on agricultural production.

The high temperature warning signal is divided into three levels, which are represented by yellow, orange and red respectively. Among them, the standard of high temperature yellow warning signal is: the daily maximum temperature is above 35℃ for three consecutive days; The standard of high temperature orange warning signal is: the maximum temperature rises above 37℃ within 24 hours; The standard of high temperature red warning signal is that the maximum temperature rises above 40℃ within 24 hours.