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Various weather systems controlling Monsoon rains
Posted on: 04/Jun/2018 12:53:12 PM
Indian seas are very active during the Southwest Monsoon season with a range of weather systems developing right from lows to depressions or even storms at times. During the time of Monsoon onset, formation of cyclonic circulations is observed mostly till June while depressions dominate thereafter.
During the onset phase, the Pre-Monsoon heat which is retained by the seas remain as the release process is slow, which is precisely why cyclonic storms form.
However, after that, due to persistent rainfall activity and lower temperatures, heat potential decreases in the months of July and August. Thus, frequency of cyclonic storms is very less.
The Bay of Bengal systems are more active as compared to the Arabian Sea.
The ratio of storm development is 1:10 which is also a rare scenario in July as well as August. Even if they do develop in the Arabian Sea, they do not move inland due to the unfavourable wind pattern.
As long as these systems do stay close to the coast, they give rains. However, when these systems move away, not only do the rains reduce, but Monsoon rains are also affected adversely by wind pattern.
Talking about the Bay of Bengal, it is landlocked mostly by the Indian coastline as well as Bangladesh and Myanmar. All the systems that form in the Bay move inland due to favourable wind pattern. Two thirds of the season, most systems form in the North of Bay of Bengal and do not see much sea travel moving inland. The frequency of depressions is quite high, even three in a month.
Most of these systems do not have the steam to go up to North India including areas of Rajasthan, Punjab, Haryana, and Delhi as they exhaust by the time they reach there. However, the Western Disturbances present in the Western Himalayas energize these systems causing rains over the region.
A lot of these systems form in the Bay of Bengal during the withdrawal month of September. In fact, by the fag end of September, cyclonic storms begin to form again.
The third kind of systems that occur are known as the INSITU formation which form over the land itself. During the Monsoon months, moisture is available in abundance as moisture is pumped from both the seas which results in the formation of systems over land and give enough rains.
These are the various types of systems which are responsible for giving Monsoon rains across the country and are responsible for deciding the performance of Monsoon.
Courtesy: skymetweather.com
