Weather characteristics and causes of Ala in western India

The source of the summer southwest monsoon in the Indian Peninsula is the Somali cross-equatorial airflow, which itself comes from the low-latitude trade winds in the South Indian Ocean. In addition, the air flows through the North Indian Ocean and the South Arabian Sea, absorbing a lot of water vapor, so there is plenty of water in the rainy season.

In Pakistan, although there is monsoon activity, the source of wind is not Somali cross-equatorial airflow, but from Arabian Peninsula and Iranian Plateau. These lands have been dry for a long time and there is not much water vapor on the surface. Even though it flows through the northern Arabian Sea, due to the relatively small water area, the air vapor is not as good as the Indian monsoon. In addition, the eastern edge of the North Africa-Iran subtropical high is located in the west of Pakistan in summer, and the northerly airflow prevails in the eastern edge of the upper subtropical high. Coupled with the influence of subsidence, it is difficult to form clouds, let alone rain.