4.RAINFALL : REGIONAL DISTRIBUTION:
The annual average rainfall of India is 89 CM over a long period average. LPA is calculated in India as the average of rainfall over a period of 50 years from 1951 to 2000. According to Indian Meteorological Department, normal monsoon is within the range of 89 CM Plus/ minus 4%.
If Earth’s surface were perfectly uniform, the long-term average rainfall would be distributed in distinct latitudinal bands, but the situation is complicated by the pattern of the global winds, the distribution of land and sea, and the presence of mountains. Because rainfall results from the ascent and cooling of moist air, the areas of heavy rain indicate regions of rising air, whereas the deserts occur in regions in which the air is warmed and dried during descent. In the subtropics, the trade winds bring plentiful rain to the east coasts of the continents, but the west coasts tend to be dry. On the other hand, in high latitudes the west coasts are generally wetter than the east coasts. Rain tends to be abundant on the windward slopes of mountain ranges but sparse on the lee sides.
the amount of vary significantly in different region within India.the rainfall pattern is influenced mainly on account of the following factor;
▪︎ pressure belt
▪︎physical features
▪︎the moisture carried by winds reduces from south to north and from east to west.
1.Area of high rainfall.
▪︎windward sides of western Ghats .
▪︎ meghalaya hills .mawsynram and cherrapunji are the wettest places in the world. These places recieve an annual average rainfall of nearly 1100 cm.
2.medium rainfall (100 -200 cm)
▪︎parts of southern Gujarat
▪︎eastern Tamil Nadu
▪︎odisha
▪︎jharkhand
▪︎bihar
▪︎madhya pradesh
▪︎ Eastern Uttar Pradesh
▪︎ West Bengal
- Low rainfall (50-100 cm)
▪︎ Western Uttar Pradesh
▪︎ Punjab
▪︎ Haryana
▪︎ Eastern Rajasthan
▪︎ northen Gujarat - Inadequate rainfall (less than 50 cm)
▪︎ Telangana
▪︎ interior parts of Karnataka and Maharashtra
▪︎ Jammu and Kashmir
▪︎ Western Rajasthan
▪︎ Saurashtra region of Gujarat
The part of Rajasthan that is east to the Aravallis sufficient rainfall and is fertile in nature. Eastern Rajasthan includes fertile Plains of Jaipur and Udaipur. The central part of Rajasthan is Bagar. The western most part of Rajasthan is Thar desert.
The Eastern part of Rajasthan is on the windward side of Aravallis, where as the central and western most part of Rajasthan are on the leeward side of the Aravallis.
The interior part ofMaharashtra ,Karnataka, and Telangana receives less than 50 cm rainfall because these regions are located in the rain Shadow region of the Western Ghats.
Variability of Rainfall:-
The degree to which rainfall amounts vary across an area or through time is an important characteristic of the climate of an area. This subject area in meteorology/climatology is called “rainfall variability.” There are two types (or components) of rainfall variability, areal and temporal. The study of the latter is important in understanding climate change.within india,the rainfall variability is higher in regions where south-west monsoon reaches later. Thus, regions with higher rainfall have less variability in rainfall and the regions with lesser rainfall have higher variability in rainfall.
CLIMATIC REGIONS OF INDIA:-
India is often referred to as a country with tropical monsoon type of climate. The large size of India, its latitudinal extent, the presence of the Himalayas in the north, and the Indian Ocean, Arabian Sea and Bay of Bengal in the south have resulted in great variations in the distribution of temperature and precipitation in the subcontinent of India.A systematic study of the climatic divisions of India was attempted for the first time by H.E. Blandford—the first Director General of the Indian Meteorological Department—in 1889, who discovered that all types of climates found in the world are present within the subcontinent of India. This classification based on temperature and rainfall of a few selected stations of India was almost an overgeneralisation.
Primarily, Indian climate is mainly of the monsoon type, but India can be further divided into eight climatic regions:
- Monsoon with short dry season: West Coast of India South of Goa on account of break in monsoon.
- Monsoon with dry summers and wet winters: coast of Tamil Nadu.
- Tropical Savannah: Central part of Peninsular plateau are Telangana and interior parts of Maharashtra and Karnataka.
- Semi-arid climate: South parts of the Punjab and Haryana ,Central Rajasthan, and north- Eastern Gujarat.
- Hot desert: Western Rajasthan.
- Cold humid winter with short summer: north-east ,except plains of Assam.
- Polar type: Jammu and Kashmir korma Uttarakhand Himachal Pradesh .
- Monsoon with dry winters: remaining parts of the country.
