The Himalayas have a profound effect on the climate of the Indian subcontinent and the Tibetan plateau. It prevents frigid, dry Arctic winds from blowing south into the subcontinent, which keeps South Asia much warmer than corresponding temperate regions in the other continents. It also forms a barrier for the monsoon winds, keeping them from traveling northwards, and causing heavy rainfall in the Terai region. The Himalayas are also believed to play an important part in the formation of Central Asian deserts such as the Taklamakan and Gobi deserts.
The mountain ranges also prevent western winter disturbances from Iran from traveling further, resulting in snow in Kashmir and rainfall for parts of Punjab and northern India. Despite being a barrier to the cold northerly winter winds, the Brahmaputra valley receives part of the frigid winds, thus lowering the temperature in the northeast Indian states and Bangladesh. These winds also cause the North East monsoon during this season for these parts.
In turn, the weather phenomenon called Jet Stream affects our image of the highest peaks on earth. The strong stream of winds from the west passes through Everest, creating a familiar plume of snows blowing from the summit, and visible from a great distance.
The Himalayas with dazzling pinnacles of snow-covered ranges extend for 2,250-km from the Namcha Barwa on the bend of the Tsang-po (Brahmaputra) to Nanga Parbat on the Indus. The range runs east to west up to central-Nepal and then takes a southeast to northwest direction. The average width of the Himalayas is about 200-km.
Compositions of the forests on this mighty ranges are affected by the combined effect of altitude, rainfall and latitude. The rainfall, mainly from the monsoons, decreases from the east to the west. Comparatively, in winter, due to the influence of tropical west wind drift, the northwest areas have more precipitation in the form of rain and snow. From these snow covered ranges with big glaciers, flow the great rivers that have made the Indo-Gangetic plain one of the most fertile in the world and the heart Land of India.