monsoon-rainfall-weather-and-climate | TNPSC Fuhrer Notes

Uniform Climate: The term “Uniform Climate” is also known as “British Climate.” This type of climate is neither excessively hot nor very cold.

Factors Determining Indian Climate:

Latitude, Distance from the Sea, Elevation, Monsoon Winds, Landform, and Jet Streams:

Latitudes:

India spans from 8°4’N to 37°6’N latitude, with the Tropic of Cancer (23°30’N) dividing the country into two halves.
South of the Tropic of Cancer experiences high temperatures year-round with mild winters.
North of the Tropic of Cancer has a temperate climate, with temperatures exceeding 40°C in summer and dropping near freezing in winter.

Elevation:

As elevation increases, the temperature drops by 6.5°C for every 1000 meters.
This is known as the “Normal Lapse Rate.
“Hill stations like Ooty, Mussoorie, and Shimla are cooler than the plains.

Distance from the Sea:

Proximity to the sea influences temperature and rainfall.
Peninsular India, being close to the sea, has a moderate climate with mild winters and stable temperatures throughout the year.
Central and Northern India experience extreme temperature variations, with hot summers and cold winters due to their distance from the sea.
Kochi, near the coast, maintains an average annual temperature around 30°C, while New Delhi, far from the coast, often exceeds 40°C.
Coastal areas have high humidity, leading to significant rainfall.
Kolkata, near the coast, receives 119 cm of annual rainfall, while Bikaner (Rajasthan), inland, records less than 24 cm.

Monsoon Winds:

Monsoon winds are the most significant factor influencing India’s climate.
These winds change direction according to the seasons.
India experiences the effects of monsoon winds for most of the year.
In India, the sun’s vertical rays strike in mid-June, although summer ends by late May.
The onset of the Southwest Monsoon brings down temperatures and causes moderate to heavy rainfall across different regions of India.
Similarly, Southeast India is influenced by the Northeast Monsoon.

Weather refers to the atmospheric conditions at a specific place, while climate refers to the average weather patterns in a region over approximately 30 to 35 years.

Topography:

India’s topography significantly impacts climate elements like temperature, atmospheric pressure, wind direction, and rainfall.
The Himalayas block cold winds from Central Asia, keeping the Indian subcontinent warmer even during the winter.
As a result, North India experiences a tropical climate.
During the Southwest Monsoon, the Western Ghats’ western slopes receive heavy rainfall.
In contrast, large areas of Maharashtra, Karnataka, Telangana, Andhra Pradesh, and Tamil Nadu receive less rainfall as they lie in the rain shadow region or leeward side of the Western Ghats.
During this season, Mangalore on the west coast receives about 250 cm of rainfall, while Bengaluru, located in the rain shadow region, receives only 50 cm.

Jet Streams:

Jet streams are fast-moving air currents in the upper layers of the atmosphere.
According to the Jet Stream Theory, the Subtropical Westerly Jet moves from the vast plains towards the Tibetan Plateau, leading to the formation of the Southwest Monsoon.
The Lower Jet Streams are also instrumental in the formation and retreat of the Southwest Monsoon, creating low-pressure systems.

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