Monsoon is an air mass that is responsible for exceptionally heavy rainfall in many regions of the world including South East Asia, South Asia, and parts of Australia and Africa. It is a very important rain bearing system on which lives of billions of people are dependent.
Conditions during Premonsoon Season
The Thermal Regime
The conditions can, perhaps, be best described by observing the Indian Monsoon. The preceding months before the monsoon are termed as pre monsoon months. The typical region of India under study is central India. The premonsoon here lasts from the middle of march to the middle of June.
Temperature start to rise sharply as soon as the middle of March comes. By the end of the month the highs are as high as 100 F. By the middle of April they have crossed 110 F and by the early part of June, temperatures up to 120 F must be expected.
The precipitation in this season is exceptionally low and some years pass in central India without recording any sort of rainfall. The air is very dry indeed and the relative humidity, sometimes falls to as low as 5 percent in the afternoons. Hot air blows, most of the time and heat waves of severe intensity are the norm. Normally a spell of intense heat wave is broken down by a severe dust storm that brings some relief as far as temperature is concerned but raises the heat index as a result.
The natural consequence of intense temperatures over the great land mass of central India is that a deep low pressure develops over the region that attracts moisture laden winds from Bay of Bengal and the East Indian ocean. These moist winds rush to fill the gap and are, in general, called the monsoon winds.
In Thailand, Myanmar and else ware in south Asia the general conditions are the same but there are a few exceptions. In the first place, temperatures, do not rise as sharply as those of Central India. Secondly dust storms, if ever they occur are not as violent as those of Central India and thirdly premonsoon season is much shorter here than that of India.
In short the premonsoon season is the preparation for the monsoon season with very high temperatures an almost complete absence of rainfall and a very dry air indeed. This season, in India, especially, must be avoided by the foreigner owing to increased risk of sunstroke due to exceptionally high temperatures.
The Distribution of Monsoon Rain in Pakistan
The Arrival Of The South West Monsoon
The Exceptional Pre Monsoon Season Of Lahore