Seasons of Tropical Monsoon Climate

This article throws light upon the three distinct seasons of tropical monsoon climate. The seasons are: 1. The cool, Dry Season 2. The Hot Dry Season 3. The Rainy.

Tropical Monsoon Climate: Season # 1.

The Cool, Dry Season (October to February):

Temperatures are low 76°F. in Bombay and only 50°F. in Punjab, with heavy sinking air. Frosts may occur at night in the colder north. The centre of high pressure is over the Punjab. Out blowing dry winds, the North-East Monsoon, bring little or no rain to the Indian sub-continent. However, a small amount of rain falls in Punjab from cyclonic sources and this is vital for the survival of winter cereals.

Where the North-East Monsoon blows over the Bay of Bengal it acquires moisture and thus brings rain to the south-eastern tip of the peninsula at this time of the year. For instance, in Madras 50 inches of rain falls during October and November, accounting for half its annual rainfall.

Tropical Monsoon Climate: Season # 2.

The Hot Dry Season (March to Mid-June):

As can be seen from Fig. 126(a), the temperature rises sharply with the sun’s northward shift to the Tropic of Cancer. Bombay has a mean May temperature of 86°F. which is considered moderate, for many parts of India are even hotter.

The heat is so great that schools and colleges are closed. The stifling heat and the low relative humidity make outdoor life almost unbearable. Day temperatures of 95°F. are visual in central India and the mean temperature in Sind may be as high as 110°F. Coastal districts are a little relieved by sea breezes.

There is practically no rain anywhere. By May, the temperature is so high that an intense low pressure zone is set up in north-west India. Dust-storms are frequent, followed by long awaited rainstorms that ‘break’ by the middle of June. The transitional period between ‘no rain’ and ‘plenty of rain’ is over.

Tropical Monsoon Climate: Season # 3.

The Rainy Season (Mid-June to September):

With the ‘burst’ of the South-West Monsoon in mid-June, torrential downpours sweep across the country to the delight of everybody. Almost all the rain for the year falls within this rainy season. For example in Bombay 19.9 inches are recorded in June, 24 inches in July, 14.5 inches in August and a further 10.6 inches in September. As much as 95 per cent of the annual rainfall is concentrated within four months.

This pattern of concentrated heavy rainfall in summer is a characteristic feature of the Tropical Monsoon Climate. The torrential down­pours have an immediate impact on the local tem­perature. They lower the temperature considerably.

The mean temperature for Bombay is 86°F. in May but only 81°F. in July. In the north the drop is even greater, as much as 13°F. Some of the windward stations on the Himalayan foothills have very heavy rainfall, though this is partly orographic. Cherrapunji has an average annual rainfall of 425 inches and a record of 905 inches in 1861.