Geographical problems. Why is summer dry weather controlled by high air pressure?

At this time, the high pressure is not on land, but India has formed the Indian low pressure on land. At this time, the high pressure in the Pacific Ocean is Hawaiian high, and the summer monsoon blows from the ocean, which is the wind direction from high pressure to low pressure. During the summer drought, this high-pressure ridge extends all the way to the middle and lower reaches of the Yangtze River, so it forms a high-pressure ridge and precipitation is scarce.