In high school geography, we often say that the subtropical high in July controlled the middle and lower reaches of the Yangtze River to form a summer drought. Why does the subtropical high not affect

In high school geography, we often say that the subtropical high in July controlled the middle and lower reaches of the Yangtze River to form a summer drought. Why does the subtropical high not affect the middle and upper reaches of the Yangtze River? 1. Most of the middle and upper reaches of the Yangtze River belong to alpine areas, with high terrain and thin atmosphere, which is not conducive to the formation of high pressure areas;

2. High altitude, low temperature and little updraft are not conducive to the formation of high pressure;

To sum up, it is mainly influenced by topography. Because the subtropical high is caused by the direct sunlight movement of the Tropic of Cancer caused by the earth's rotation, a fault zone is formed at high altitude.