Climate of India
* In India, the Tropic of Cancer passes through the central part of the country.
* India has both tropical and subtropical climates.
* Altitude refers to the height above sea level.
* The Himalayas influences the climate of the Indian subcontinent by protecting it from the cold air mass of Central Asia.
* The climate and related weather conditions in India are controlled by the following atmospheric conditions:
Pressure and Surface Winds
* Upper air circulation
* Western cyclonic disturbances and tropical cyclones
* The earth’s rotation causes the Coriolis force which tends to turn the flow of air.
* Jet streams are a narrow belt of high altitude westerly winds that blow in the troposphere.
Climatic Controls
* Weather describes the day-to-day meteorological condition such as wind, temperature, cloudiness, moisture, rainfall etc. affecting a place.
* Climate is the average weather usually taken over a 30-year period.
* The basic elements of weather are wind, temperature, air pressure, precipitation and moisture.
* The six factors that influence the climate of a region are latitude, altitude, pressure and wind system, distance from the sea, ocean currents and relief features.
The Mechanism of Monsoons
* The climate in India is strongly influenced by monsoon winds. The word monsoon refers to the season in which the wind system reverses completely. They are experienced in the tropical area roughly between 20° N and 20° S.
* Due to the atmospheric conditions encountered on the way, the monsoon winds are not steady, but are pulsating in nature.
* The winter monsoon is experienced in the states of Tamil Nadu, Kerala and Andhra Pradesh in the first week of January.
* The sudden increase in the rainfall that continues for several days is called the ‘burst’ of the monsoon.
* The monsoon arrives at the southern tip of the Indian Peninsula generally by the first week of June.
* By early September, the monsoon starts to withdraw or retreat, which is a more gradual process.
* By mid-October, it withdraws completely from the northern half of the peninsula.
* The winter monsoon is experienced in the states of Tamil Nadu, Kerala and Andhra Pradesh in the first week of January.
The Seasons of India
* The changes in the weather conditions in India can be broadly categorised into four distinct patterns
The cold weather season
The hot weather season
The advancing monsoon and
The retreating monsoon
* India has cold weather in the winters that begin in mid-November and lasts till February.
* December and January are the coldest months of winter.
* Winters are more severe in the northern parts of India, while the southern parts of
* India do not experience very low temperatures.
* Frost is a common phenomenon in the northern plains, while the higher slopes of the Himalayas experience snowfall.
* In most parts of India, the weather during winter is dry. However, the coast of Tamil Nadu receives some amount of rainfall during the winter.
* The sea has a moderating influence over the peninsular region of India.
* Hence, there are no drastic seasonal variations in temperature pattern, and winters are not as distinct as in the north.
* The hot weather season in India refers to the summers that begin in March and lasts till mid-June.
* ‘Loo’ that are strong, gusty, hot, dry winds that blow during the day over north and north-western India are a striking features of the hot weather season.
* In northern India, dust storms are also very common during the month of May.
* Pre-monsoon showers that are experienced at the close of the summer season are common, especially in Kerala and Karnataka. They are often referred to as ‘mango showers’ as they help in the early ripening of mangoes.
* The advancing monsoon in India refers to the rainy season that lasts for a period of four months from June to September.
* The trade winds of the southern hemisphere that originate over the warm subtropical areas of the southern oceans bring the south-west monsoon winds into India.
* ‘Breaks’ in rainfall, a characteristic feature of the monsoon, refers to the alternating wet and dry spells of rains.
* The Indian monsoon is very unpredictable.
* The farming schedule of millions of farmers all over the country, which is dependent on the monsoons, can sometimes get disturbed.
* The retreating monsoon refers to the transitioning of the season from hot rainy to dry winter conditions. It lasts from October to December.
* The distribution of rainfall varies drastically from region to region. Major variations can also be seen in the annual precipitation from year to year.