What are the characteristics of rainy season?

Meiyu is a natural weather phenomenon, so do you know what are the characteristics of Meiyu season? Let's look at the characteristics of the rainy season. Welcome to reading.

What are the characteristics of rainy season (1)? The basic reason for the advance of the rainy season is that the northward jump of the western Pacific subtropical high occurs in advance, which makes the main rainfall belt in the eastern half of China suddenly move from the south of Nanling to the middle and lower reaches of the Yangtze River. Meiyu like 197 1 started on May 26th, more than half a month earlier than normal. The turning point of the weather this year began in the tropics.

In late May, three typhoons occurred on the tropical ocean surface of the northwest Pacific Ocean. These typhoons occurred on the south side of the subtropical high and moved northwest. This activity is like the subtropical high being pushed northward, which makes the high rise northward. During this period of change, the high-altitude westerly jet moved northward, and the plum rains in the middle and lower reaches of the Yangtze River suddenly began. It should be noted that the early northward jump of subtropical high is not entirely caused by thermal typhoon activities, and other reasons can also lead to its early northward jump. As long as the subtropical high moves to the coast of South China ahead of time and is stable, it will cause? Morning plum rain? .

(2) Late Meiyu: The southern branch of westerly jet is strong and stable in early summer in some years. In June, a strong westerly wind was maintained in the middle troposphere from the Yangtze River valley in China to the Pacific Northwest in southern Japan. Its existence has restrained the northward uplift of the subtropical high in the northwest Pacific Ocean, making it impossible to establish the rain belt in the middle and lower reaches of the Yangtze River for a long time. In this way, the rainy season came late. For example, 1982, the rainy season in the middle and lower reaches of the Yangtze River only started on July 9, which is the case.

Before June 20th this year, westerly jet was southerly and the subtropical high was southerly. Around the 20th, the subtropical ridge of the northwest Pacific Ocean extending along the southeast coast of China was once strengthened and carried northward to the coast of South China. Three or five days of rainy weather appeared in the middle and lower reaches of the Yangtze River. However, this change is not a seasonal turning point. The main body of the subtropical high in the northwest Pacific has not moved northward, especially the westerly wind in the south branch still stays near 30 degrees north latitude. Under the influence of westerly jet, the cold air moved southward, and the subtropical high quickly withdrew southward. It was not until early and late July that the westerly jet over East Asia suddenly retreated northward, causing the subtropical high over the eastern coast of China and Japan to jump northward obviously, and the Meiyu began to come.

(3) Extra-long plum rain: What is the main reason for the extra-long plum rain? No plums? Especially late, such as 1954, the rainy season didn't end until the end of July and the beginning of August. What is the reason why the plum rain can't end for a long time? This year, there were many anomalies in the characteristics of atmospheric motion in the whole northern hemisphere. From the perspective of Asia and the Pacific Northwest, there are two main aspects: First, during June-July of 1954, the subtropical high in the Pacific Northwest was much southward than normal. Especially in July, the ridge line of subtropical high in the middle troposphere along the East Asian coastal area is basically along the north latitude 18 degrees, about 800 kilometers south than normal.