Why did it rain heavily in Chongqing in April? Where does the cold air come from?

Why did it rain heavily in Chongqing in April? The main reasons are as follows:

First, April is the rainy season. Influenced by the northern airflow and the humid climate in Chongqing, the average annual precipitation is relatively rich, ranging from 1000 ~ 1350mm in most areas, and the precipitation is mostly concentrated from May to September, accounting for about 70% of the annual precipitation. The main climatic characteristics can be summarized as follows: warm winter and early spring, hot summer and cool autumn, four distinct seasons and long frost-free period; The air is humid and the precipitation is abundant; Weak solar radiation and short sunshine time; There are more clouds and less frost and snow; Light and warm water are in the same season, and the three-dimensional climate is remarkable and the climate resources are rich.

Secondly, Chongqing is affected by subtropical high all the year round, which belongs to subtropical monsoon climate, with warm winter and hot summer. The average temperature in winter is 6-8 degrees, the average temperature in spring and autumn is around 18 degrees, and the average temperature in summer is between 29-3 1 degrees. Due to the abundant precipitation brought by subtropical high, there are abundant rain sources. Chongqing is surrounded by mountains and has a lot of rainfall.

Third, Chongqing is located in a low-lying basin. This topography makes it difficult for heat to spread and accumulate in the basin. At this time, when the cold air and wet air outside meet, rain clouds will form. Because the topography of the basin limits the convection of wind, warm and humid air cannot dissipate, and more water vapor is accumulated in the basin. As long as cold air is added, it is easy to produce precipitation. It is this special geographical location and the influence of subtropical high that makes Chongqing form its own unique microclimate, which is rainy and sultry.

Where does the cold air come from? There are three reasons:

First, the south branch trough is active. The South Branch Trough is an important weather system affecting the south of China, which will not only bring precipitation, but also cause strong convective weather such as heavy rain and strong wind.

The second reason is that the transportation of warm and humid airflow in southwest China makes water vapor abundant and is a powerful driving force for rainfall.

The third reason is that at present, our city is in midsummer, and summer is also the season with the most thunder and lightning in the whole year. The alternation of cold and hot makes the temperature drop quickly, and the updraft rises quickly and falls slowly, which leads to the inability of airflow to disperse.

Extended data:

There is more precipitation in Chongqing from May to September, accounting for about 70% of the whole year, especially in spring and summer, which is known as "night rain". In fact, "late rain" refers to the mountainous areas in southwest China (including Sichuan Basin) where it rains at night. The amount of night rain in these places generally accounts for more than 60% of the annual precipitation. For example, Chongqing and Emei Mountain account for 665,438+0% and 67% respectively, while Zunyi and Guiyang on the Guizhou Plateau account for 58% and 67% respectively. There are also many night rains in other parts of China, but the number, quantity and influence range of night rains are not as good as those in Daba Mountain and Sichuan Basin.