Rainfall distribution worldwide varies due to diverse climatic conditions in different regions. Few areas receive high rainfall whereas the other few encounter scanty rainfall. The areas surrounding tropical and equatorial regions too receive high rainfall. The annual average rainfall of the world is 100 cm.

Global Distribution of Rainfall

• Distinct parts of the earth’s surface receive varying quantities of rainfall throughout the year, as well as during different seasons.
• In general, rainfall decreases significantly as one travels from the equator to the poles.
• Rainfall falls more heavily on the world’s coasts than it does on the continents’ interiors.
• Because seas are excellent water providers, they receive more rainfall than landmasses around the world.
• Eastern beaches (35°-40° N and S) receive higher rainfall, gradually decreasing towards the west.
• Rainfall is initially higher on western continental borders (45°-65° N and S) due to westerlies and decreases eastward.
• Coastal plains experience higher rainfall on the windward side but less on the leeward side near parallel mountains.
• The world’s principal precipitation regimes are identified as follows, based on the total quantity of yearly precipitation.
• Equatorial belt, western cold temperate zone mountains’ windward slopes, and coastal monsoon regions get 200+ cm rainfall yearly.
• Interior continental areas receive moderate rainfall varying from 100 – 200 cm per annum. The coastal areas of the continents receive moderate amounts of rainfall.
• Tropical land’s center and temperate land’s east and interior receive 50-100 cm annual rainfall.
• Areas lying in the rain shadow zone of the interior of the continents and high latitudes receive very low rainfall – less than 50 cm per annum.
• Seasonal distribution of rainfall provides an important aspect to judge its effectiveness. Equatorial belt and western cool temperate regions have evenly distributed rainfall throughout the year.

Distribution of Rainfall in India

• The average annual rainfall in India is about 125 cm, but it has great spatial variations.
• Areas of High Rainfall : The highest rainfall occurs on the west coast, Western Ghats, and northeast sub-Himalayan areas, including Meghalaya hills. Here the rainfall exceeds 200 cm. In some parts of Khasi and Jaintia hills, the rainfall exceeds 1,000 cm. In the Brahmaputra valley and the adjoining hills, the rainfall is less then 200 cm.
• Areas of Medium Rainfall : Southern Gujarat, east Tamil Nadu, northeast Peninsula (Odisha, Jharkhand, Bihar), eastern Madhya Pradesh, northern Ganga plain, Cachar Valley, and Manipur receive 100-200 cm rainfall.
• Areas of Low Rainfall : Western Uttar Pradesh, Delhi, Haryana, Punjab, Jammu and Kashmir, eastern Rajasthan, Gujarat and Deccan Plateau receive rainfall between 50-100 cm.
• Areas of Inadequate Rainfall: Parts of the Peninsula, especially in Andhra Pradesh, Karnataka and Maharashtra, Ladakh and most of western Rajasthan receive rainfall below 50 cm.

Rainfall variability is a crucial aspect of an area’s climate. This subject area in meteorology/climatology is called “rainfall variability.

• Owing to the nature of monsoons, the annual rainfall is highly variable from year to year. Regions with low rainfall, like Rajasthan, Gujarat, and leeward Western Ghats, exhibit high variability.

Distribution of Rainfall in world,Distribution of Rainfall in world,Distribution of Rainfall in world

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