As this area is located in the mid latitude westerly belt, there is a gap in the north of Tianshan Mountains (the west side of Junggar Basin to the north of Tianshan Mountains is low), and water vapor from the Atlantic Ocean can enter this area. In addition, the humid air flow from the Arctic Ocean, the northern slope of Tianshan Mountains is lifted by the terrain, forming precipitation. Therefore, the precipitation on the north slope of Tianshan Mountain is more than that on the south slope.
Reasons for More Rainfall on the North Slope of Tianshan Mountains than in the South
① Affected by water vapor from the Atlantic Ocean and Arctic Ocean;
② It is located on the windward slope of the mountain, which has a lifting effect on water vapor.
Analysis of precipitation in the south and north of Tianshan Mountains
That is to say, the precipitation on the northern slope of Tianshan Mountain is more than that on the southern slope of Tianshan Mountain, which makes the water condition on the northern slope of Tianshan Mountain better than that on the southern slope, so there are forests growing, while the southern slope is not enough to grow forests due to the lack of water. The main reason for more precipitation on the northern slope of Tianshan Mountains is that the terrain of Junggar Basin to the north of Tianshan Mountains opens to the northwest and is not completely closed, so that the prevailing westerly wind from the Atlantic Ocean and the air flow from the Arctic Ocean can enter along the mountain pass and rise southward to meet the northern slope of Tianshan Mountains, thus forming topographic rain and generating precipitation. The Tarim Basin to the south of the Tianshan Mountains is surrounded by the Tianshan Mountains and the Kunlun Mountains. The terrain is closed, water vapor is difficult to enter, and precipitation is scarce, which cannot meet the growth of forests.