Rainfall distribution and variability across India

• North-eastern States: The north-eastern states, including Assam, Meghalaya, Mizoram, and Nagaland, receive abundant rainfall during the monsoon. These states are influenced by both the southwest and northeast monsoons, resulting in high precipitation levels.

Regions with moderate rainfall 

• Indo-Gangetic Plains: The northern plains, including states like Punjab, Haryana, Uttar Pradesh, and Bihar, experience moderate to low rainfall during the monsoon. The Himalayan foothills, however, receive higher precipitation.

• Central India: States like Madhya Pradesh and Chhattisgarh, experiences moderate rainfall during the monsoon. The region is influenced by the retreating monsoon, which brings rainfall during the post-monsoon period.

Regions with low rainfall

• Western and Northern India: Western and north-western parts, including Rajasthan and Gujarat, receive low rainfall. These areas are arid to semi-arid, and the Thar Desert in Rajasthan experiences minimal precipitation.

• Ladakh: high-altitude desert with low rainfall is due to region's high altitude and its location in rain shadow of the Karakoram Mountains.

Factors responsible for uneven distribution of rainfall in India

• Distance from the Sea: Areas along the coast get more rainfall when contrasted with those areas which further away from the ocean this is because moisture-laden winds from the sea release their moisture as rain when they encounter the coastal landmasses.

• Example: Coastal areas like Kerala, Goa, and Maharashtra receive heavy rainfall due to their proximity to the Arabian Sea.

• Mountain ranges: As moist winds from the sea rise over mountains, they cool down, leading to condensation and precipitation. Areas on the windward side of mountains receive heavy rainfall and areas on the leeward side of mountains receive less rainfall due to the rain shadow effect.

• Example: Presence of western Ghats acting as a barrier resulting in heavy rainfall on the windward side and drought like dry condition in leeward side in parts of Tamil Nadu, Andra etc.

• Monsoon winds and direction: The Bay of Bengal branch of the monsoon brings more rainfall to the north-eastern states due to the orographic effect, while the Arabian Sea branch brings rainfall to the western coast. The interior regions, away from these branches, receive comparatively lower rainfall.

• El Niño-Southern Oscillation (ENSO): El Niño events typically lead to reduced rainfall in India, while La Niña events typically bring increased rainfall.