Since July, large-scale and persistent high temperature weather has occurred in northwest my country, southern North China, western and northern Huanghuai and other places.

Someone asked, is this round of high temperature directly caused by the "thermal dome"?

To answer this question, we must first understand what a "thermal dome" is."Hot dome" is a description of the phenomenon of extreme high temperature weather, and is not a well-defined academic term for meteorology.It is a summary and visual popular science expression by forecasters on the physical causes related to high temperature weather.It describes a large-scale high-pressure system that stably controls a certain area for a long time, covering it like a "pot lid" in the sky, making it difficult for heat to spread outwards, causing continuous temperature rise.Therefore, it cannot simply be said that the epicycle high temperature is directly caused by the "thermal dome".To be precise, the recent high temperatures in northwest my country, North China and other places are caused by the control of high pressure ridges.Under high-pressure control, the system is stable and less active, the sky is clear and less cloudy, the solar radiation is strong, the air sinks and heats up, and heat continues to accumulate near the ground, eventually leading to extreme high temperature weather in some areas.

The important systems that affect my country’s summer high temperatures include subtropical high pressure, blocking high pressure, etc.Subtropical high pressure mainly affects the Jianghuai, Jiangnan, South China, Sichuan Basin and other places in my country; blocking high pressure occurs more often in mid-to-high latitudes. It is characterized by stability and little movement, making a certain area stay sunny, hot and dry for a long time.The persistent high temperatures in northwest my country, North China and other places are sometimes related to high pressure ridges or blocking high pressure. These areas will have a "thermal dome" effect.The manifestation of the warming of the subtropical high pressure and blocking high pressure is consistent with the formation mechanism of the "hot dome" effect, and can be considered to be the driving system that causes the "hot dome" phenomenon.

How is the "heat dome" effect formed?

First, the air sinks under high pressure control. During the sinking process, the air is compressed and heated.Secondly, with clear skies and few clouds, the solar radiation is stronger and the earth's surface is continuously heated.Third, the system is stable and moves less, and the heat diffusion in both horizontal and vertical directions is limited, and heat continues to accumulate in a certain area.The superposition of several aspects can easily form a large-scale "hot dome" effect.The "heat dome" effect mainly occurs in summer, but under certain conditions, some areas may also experience abnormally warm weather in winter.

In recent years, we feel that it is getting hotter and hotter. This is actually the result of the joint action of weather scale systems and climate change.In the short term, it is because a certain high-pressure system is stable and less active, causing sunshine, subsidence, warming and heat accumulation.In the long term, global warming will increase the basic temperature, and factors such as soil drought and urban heat islands will further amplify the human body's experience of high temperatures.(The author Liu Xiaobo is the chief forecaster of the Central Meteorological Observatory, and was interviewed and compiled by our reporter Jiang Xuehong)