Geographically India lies in the north tropical and subtropical belts. The different types of climate in India are influenced mainly by its geography. The sea surrounding the three sides, the mountains in the north, and the physiography of the mainland greatly modify its climate.
Physiography of India
The Indian climate is essentially monsoon. Its physiographic features at different places change this climate. The southern peninsular India lies on the western side, with fairly high hills of western ghats and lower interrupted hills on the eastern side, known as eastern ghats.
In between the two, is a plateau of low elevation. In the central part of the country, several hills are found scattered in various places. They slope northwardly into the great Indus and Gangetic plains.
Further north are the Himalayan ranges on the eastern side of Naga Hills and the western side by the Hindikush. Another physiographic feature is the sandy plain in the northwest, called the Thar desert. Thus temporary and tropical climates are met within the country.
Different Types of Climate in India
There are four seasons in India.
- Cold Season
- Hot Season
- Wet Season
- Season of retreating monsoon
Cold Season
The cold season starts in December and lasts till the end of February. During this period, low pressure develops south of the equator. It produces cool and dry winds in the northern hemisphere. They pass towards the equator and are commonly called Northerlies.
India is however protected from colder winds, coming from the Siberian region by the Himalayas. However, Westerlies, originating from the Mediterranean area pass eastwards over the Prussian Gulf and enter north India.
It produces cyclonic conditions and causes moderate rain in Punjab, Haryana, Delhi, Himachal Pradesh, Jammu and Kashmir, Uttar Pradesh, Uttarakhand, Rajasthan and Madhya Pradesh. Thunderstorms and hailstorms are often seen during this period. The latter can be harmful to the vegetation. It occurs mainly in the hilly traits while the higher ranges experience hail and snow.
Mid-January temperature can be 10 degrees Celcius in the north, 15.6 in the Gangetic plains, and about 24 degrees in the south. Therefore, the weather is warm and fine in the southern peninsula but can be extremely cold in the north. Many trees shed their leaves in this period. Frost is rare in the south but occasionally occurs in the hilly traits.
Hot Season
The summer season in India starts in March and lasts till the end of May. During this time, the temperature rises rapidly in the initial month and can reach up to 48 degrees by the end of the month in the southern peninsula.
In the northeast, April-May is the hottest period and northwest India experiences the hottest time in May-June. It is quite common to record a day temperature of 43 degrees and many northwestern areas can have up to 48 degrees.
Atmospheric humidity decreases during this period. Pressure also reduces, and dust storms will also be common. These conditions will have a desiccating effect on the vegetation. Sand storms are observed in the northwestern Tahr region. In some places, the wind can become violent and develop tornadoes. They not only uproot the vegetation but also cause large-scale destruction of property.
Some southern areas adjacent to the sea receive rain during this period. Since it coincides with the appearance of mango crops, it is often called a Mango shower.
Wet Season
The decrease in air pressure during April-May in the northern hemisphere induces winds from the south of the equator to the north. This is called southeastern trade winds. As they pass over the Indian Ocean, the trade winds become water vapors.
Due to the air circulation of India, the direction of southerlies gets deflected to the west. They are therefore also called Southwest monsoon. The monsoon wind coming from the Arabian Sea has three branches.
- Southern branch causing extensive rain over western ghats
- The middle branch passes along Madhya Pradesh
- The northern branch passes to Gujarat and Rajasthan where it does not cause much rain because of the lack of mountain range.
The monsoon from the Bay of Bengal produces rain in larger parts of India. It first strikes the mountains, and peaks bordering eastern states and produces heavy rainfall. Cherapunji receives the maximum rainfall in the world. Soon after the first heavy burst, the monsoon takes westward parts along the Himalayan ranges, Delhi, and adjoining areas.
Monsoons from the Arabian Sea and the Bay of Bengal meet at the beginning of July. They will be sufficiently weakened by this time so the rainfall will be moderate. Therefore, the wettest period in India (except the eastern coast) is between July and August.
Since this period is sufficiently hot, it is most suitable for plant growth. However, heavy rainfall in hills accompanied by snow melting and past deforestation causes heavy floods in several parts.
Season of Retreating Monsoon
It is the autumn season between October and November. It is also a season between northerly and southerly winds. Monsoon becomes inactive in north India followed by the development of high pressure there.
It pushes monsoon winds back to their place of origin. The retreat of the monsoon is slow either gradual or intermittent. It takes two to two and a half months. As it passes over the Bay of Bengal, it picks out water vapors and causes extensive rain and thunderstorms in the southeast parts, which previously remained comparatively dry. Moreover, tropical cyclones are abundant in the Arabian Sea and the Bay of Bengal.
Factors Affecting the Climate of India
Latitude
The Tropic of Cancer passes through the northern part of India. This is one of the main factors that influence and cause the different types of climate in India. The region along this latitude has a subtropical and temperate climate. Regions above this latitude get varying temperatures throughout the year. The temperature falls to extreme levels during winter, since these regions are further away from the equator.
On the other hand, the region below the Tropic of Cancer has a tropical climate that shows constantly higher temperatures throughout the year. There will be hardly any variation in the temperature. This is because of the proximity to the equator. The average temperature gradually increases from the central to the southern region.
Altitude
Areas in higher altitudes such as highland regions experience lower temperatures than other regions. Moreover, other physiographic factors such as the direction and speed of winds, rainfall, air pressure, etc., also influence the climate of a particular region. Depending on these factors, the different types of climate in India can be summarized as,
- Tropical rainy areas
- Humid subtropical areas
- Tropical Savanna
- Mountains
- Deserts
Distance from the sea
Coastal regions of India have temperate climates with higher temperatures. These regions do not have major temperature variations in a year. However, regions away from the sea and ocean experience major variations in the annual temperature and often have extreme temperatures, depending on the season.
