Why did Chongqing receive heavy rainfall in April? Where did the cold air come from?

Why does Chongqing get heavy rain in April? The main reasons are as follows:

First, April is the rainy season, by the influence of the northern air currents and the influence of the humid climate of the Chongqing region, the average annual precipitation is more abundant, most areas in the 1000 ~ 1350 mm, precipitation is concentrated in May to September, accounting for about 70% of the total precipitation of the year. The main climatic characteristics can be summarized as follows: warm winter and early spring, hot summer and cool autumn, four distinct seasons, long frost-free period; humid air, abundant precipitation; weak solar radiation, short sunshine; more clouds and fog, less frost and snow; light, temperature and water in the same season, the three-dimensional climate is remarkable, and rich in climatic resources.

Secondly, Chongqing is perennial influence by the subtropical high pressure, is a subtropical monsoon climate, warm in winter and hot in summer, the average temperature in the winter between 6 8 degrees, the average temperature in spring and fall is about 18 degrees, the summer is between 29 31 degrees. Due to the subtropical high pressure to bring abundant precipitation, rainfall is relatively more abundant, coupled with Chongqing is surrounded by high mountains, so there is more rainfall.

Third, Chongqing is in a low-lying basin, the topography of this topography so that the heat is not easy to spread out, in the basin to accumulate, when there is cold and humid air joining the outside world will form a rainfall cloud, due to the topography of the basin to limit the convection of the wind, so that the warm and humid air can not be dispersed out of the basin in the basin to accumulate more moisture, as long as there is a cold air joining the rainfall will be easy to produce. It is this special geographic location and the influence of the subtropical high pressure that makes Chongqing form its own unique microclimate, so much rainy and sultry.

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

The first one is the active south branch trough, which is an important weather system affecting the southern region of China, and it will not only bring precipitation, but also cause heavy rain, gusty winds and other strong convective weather.

The second is due to the transport of warm and humid air from the southwest, which makes the water vapor plentiful and is a strong driver of rainfall.

The third is because the city is currently at the peak of summer everywhere, and summer is also the season of the year with the most thunder and lightning, the alternation of heat and cold, so that the temperature falls fast, the rising airflow back up fast, falling slowly, resulting in the airflow can not be dispersed.

Extended information:

Chongqing has more precipitation in the months of May through September, with 70 percent of the year's precipitation falling The rainfall is about 70% of the whole year, and the night rain in spring and summer is especially bad, which is known as "Bashan night rain". The term "Bashan night rain" actually refers to the mountainous areas of southwest China (including the Sichuan Basin area) where there is a lot of night rain. The night rain in these places generally accounts for more than 60% of the annual precipitation. For example, Chongqing and Mount Emei account for 61% and 67% respectively, and Zunyi and Guiyang on the Guizhou plateau account for 58% and 67% respectively. There are other places in China that have more night rains, but the number of night rains, the amount of night rains, and the extent of their impact are not as great as in the Daba Mountains and the Sichuan Basin