What are the characteristics of summer weather changes?

When it comes to summer, the first thing people think of is heat. Summer is the period with the highest temperature of the year. There are dry and hot in inland areas and humid and hot in coastal areas. But the weather in summer can never be summed up in one word: hot. Summer is the most dramatic and complex period of the year when weather changes occur. Rainfall in most areas of our country is mainly concentrated during this period. In the past thirty years, the annual precipitation in Beijing has been 570 mm, while the precipitation in summer alone has reached 423 mm, accounting for 74% of the annual precipitation. Especially in late July and early August, heavy rains and heavy rains are often concentrated. Expect. In addition, various disastrous weather, such as thunder and lightning, hail, thunderstorms and strong winds, floods, droughts, typhoons, etc., also often occur at this time.

An important reason why summer weather is so changeable is water vapor. Abundant water vapor is the basic material for various weather changes. Speaking of water vapor, one weather system we want to introduce to you is the subtropical high. The subtropical high is a high-pressure system located on average at 35 degrees on the earth and approximately arranged along the latitude circle. The position of the subtropical high has obvious seasonal changes. In the northern hemisphere, it moves northward in summer and southward in winter. The air flow rotates outward in a clockwise direction from the high-pressure center, forming a southerly airflow in the west of the high pressure. The southerly airflow continuously transports warm and humid air from the ocean to the mainland of my country, thus providing water vapor for rainfall. Once the warm and moist air flow meets the cold air coming down from the north, it will form a wide range of rainfall. Because the position of this high pressure changes with the seasons, the rainfall belt in my country's summer half of the year advances from south to north. In autumn, the subtropical high pressure retreats southward, and the rainbands also move southward. This is the reason why the rainy season in southern my country starts early, ends late, and lasts long, while the rainy season in the north starts late, ends early, and lasts short time.

The southerly warm and moist airflow at the edge of the subtropical high can bring a large amount of water vapor to my country, but the interior of the subtropical high is often hot, dry and sunny due to the influence of downdrafts. Some abnormally moving subtropical highs are the main culprit causing widespread disastrous weather in my country.