What is a thunderstorm day? What are the places with the most average thunderstorm days in China?
The annual average number of thunderstorm days in the southeast coastal areas is lower than that in areas far from the coast at the same latitude. The annual average thunderstorm in rivers, lakes and valleys and plains is often the figure in other areas of eastern latitude. This is because the above-mentioned areas are affected by sleep, and the surface temperature is low in the second half of the year, forming unstable stratification that may cause strong convective movement, and the average number of thunderstorm days in the whole year is less. Xinjiang, Gansu, the vast desert and Gobi desert areas of Inner Mongolia, and Qaidam Basin of Qinghai have fewer annual average thunderstorm days, usually less than 10 days, which is the region with the least average thunderstorm days in China. In hilly areas with high terrain and complex terrain, the average annual thunderstorm days are often higher than those in other areas with the same latitude. For example, the average annual thunderstorm days in mountainous areas such as the Qinghai-Tibet Plateau and the western Yunnan-Guizhou Plateau are 20-40 days longer than those in inland areas of eastern latitude. It can be seen that the annual average number of thunderstorm days in China is more in the south than in the north, and there are many plains in mountainous areas and few inland coastal areas and rivers, lakes and sea basins, which have the geographical distribution characteristics of excessive drought in humid areas.
Hainan Island and Leizhou Peninsula, located at the southernmost tip of China, are relatively large islands and peninsulas. The two areas are separated by the narrow Qiongzhou Strait, and the west is connected with the Beibu Gulf. This land-sea distribution is especially beneficial to the occurrence of thermal thunderstorms in summer for six months (May-65438+1October). Because in the daytime of half a year in summer, under the strong sunlight, the land surface on both sides of the Taiwan Province Strait heats up rapidly, and the seawater temperature in the surrounding waters rises slowly due to the heat capacity of seawater, forming a thermal cycle between land and sea. The land soil is an updraft area and the ocean is a downdraft area. The formation of this land-sea thermal cycle is very beneficial to the development of rivers, so a local convective cloud system is formed around noon during the day, which is easy to cause showers.
The influence of meteorological system has also brought considerable thunderstorms to Hainan Island and Leizhou Peninsula. In spring (March-May), there are frequent activities in the low front area of South China, which bring spring thunder to Hainan Island and Leizhou Peninsula. In the four months from May to August, Hainan Island and Leizhou Peninsula are often located at the edge of the subtropical ridge in the western Pacific Ocean, and the ground is located in front of the southwest low pressure area. In this weather situation, from the ground to the sky, southerly airflow prevails in the two areas, with sufficient moisture, and a lot of unstable energy is often stored in the air. Therefore, thunderstorms often occur in these two places.