Main causes of summer monsoon onset in high-level meteorology

The definition of monsoon, as its name implies, is the seasonal wind that leads to the regular change of wind direction with the change of seasons, which is caused by the seasonal movement of the direct point of the sun from north to south.

1, (1) Reasons for the formation of the summer monsoon: When the direct point of the sun moves to the Tropic of Cancer, the northern hemisphere gradually enters a hot summer, when the temperature of the land is gradually higher than that of the ocean (due to the different properties of the land and the ocean, the temperature of the land is faster than that of the ocean), and the air pressure of the ocean is higher than that of the land (cold high pressure, warm low pressure principle). The summer monsoon is a hot and humid wind. Relative to a certain place in the monsoon region, the summer monsoon is a warm and humid air flow from the south (the principle comes from the place with high latitude of the same meridian and the temperature is lower than that of the place with low latitude), so the summer monsoon blows from the south.

The wind from the ocean contains a lot of water vapor (ocean wind is warm and humid airflow, and land wind is dry and hot or dry and cold airflow). When it is blown to the land, it will encounter heat and reach a certain saturation state, which will form rainfall.

(2) In the summer of the northern hemisphere, a high pressure formed near the Hawaiian Islands in the North Pacific Ocean, so it was named Hawaii High, while the Indian low was named because the center of the Eurasian low was in or near the Indian Peninsula.

2. It should be noted that the typical monsoon only exists in East Asia and South Asia in the northern hemisphere, and there is no monsoon in the southern hemisphere. In summer, southeast winds blow in East Asia and southwest winds blow in South Asia. The wind direction in winter is opposite to that in summer.

The principle of winter wind is actually the same as that of summer monsoon, except that the temperature of ocean and land has changed. The rapid cooling of land has formed a very strong cold high pressure in Siberia, Mongolia, the center of Eurasia (plus Eurasia is the largest continent in the world). At this time, the wind blows from Mongolia and Siberia to the surrounding areas, forming a northwest wind when it blows to East Asia, and forming a northeast wind in South Asia.

3. Some winds you ask will blow for one year, which means that the monsoon direction is basically unchanged all year round, that is, the trade winds follow the polar easterly winds (which is related to the three phoenixes and four belts around the world), the trade winds follow the polar easterly winds, the northeast winds in the northern hemisphere and the southeast winds in the southern hemisphere. The definition of trade winds refers to the winds between the Tropic of Cancer (that is, tropical areas) with the same wind direction and latitude, which are trustworthy. Under the influence of the polar cold high, the polar wind is the northeast wind (southeast wind in the southern hemisphere) from the polar cold high all the year round, and its latitude is in the polar circle.

I study geography, so I do more research, hehe. I have answered all your questions. I hope it will help you.