Geography and climate

The Himalaya constitutes the highest mountain system of the world. There is great diversification in the climatic conditions of Himachal due to variation in elevation (450-6500mtrs). It varies from hot and sub-humid tropical (450-900mtrs) in the southern Low tracts, warm and temperate (900-1800mtrs), cool and temperate (1900-2400mtrs) and cold alpine and glacial (2400-4800mtrs) in the northern and eastern high mountain ranges.
There are three main seasons in Himachal Pradesh :
1. Cold - October to February 2. Hot - March to June 3. Rainy - July to September
By October, nights and mornings are very cold. Snowfall at elevations of about 3000mtrs is about 3mtrs and lasts from December to March. About 4500mtrs, is perpetual snow. The main season is the spring from mid- Feb to March-April. The air is cool and fresh. Colourful flowers adorn the valleys, forest slopes and meadows. In the hill stations, the climate is pleasant and comfortable.The rains start at the end of June. The entire landscape becomes green and fresh. Streams begin to swell and springs are replenished. The heavy rains in July and August cause damage to erosion, floods and landslides. Dharamshala has the highest rainfall of 3400mm. Spiti is the driest area (below 50mm rainfall) being enclosed by high mountains on all sides.
Particulars and characteristics of each zone :

Particulars and Characteristics Sub Himalayan or Outer Shivalik Zone Lower Himalayan Ranges or Mid-Hill Zone Higher Himalayan Ranges or High hill Zone Cold Himalayan zone or Trance-Himalayan Zone Altitude Upto 800 meters 800 to 1,600 meters 1,600 to 2,700 meters 1,600 to 3,600 Type of Area Valley areas and foot hills Hilly and Mountain ranges Alpine zone Lahaul Spiti and Kinnaur range Climate Conditions Sub tropical Slight warm temperature Cool temperature with humidity Dry and Cold temperature (Mostly snowy area) Rainfall ( in mm. ) 1,500 mm 1,500 to 3,000 mm 1,000 to 1,500 mm 500 mm % of total geographical area 30 % 10 % 25 % 35 % % of total cultivated area 55 % 30 % 10 % 5 % Important Crops Wheat, paddy, maize, gram, sugarcane, mustard, vegetables, potato. (Rainfed, partially irrigated) Wheat, pulses, barley, maize, paddy, ginger, vegetables. (Rainfed, partially irrigated) Wheat, barley, buck wheat, millets, quality seed, temperature vegetables, potato. (Rainfed, partially irrigated) Temperature vegetables, Europian vegetables, wheat, barley buck wheat, amanthus, quality seed potato. (mostly irrigated) Fruits Guava, citrus, litchi, mango etc Plum apricot, peaches, walnut, pomegranate, pears etc Chest nut, walnut, apples, cherry etc Grapes, prunes, grapes, raisin, chilgoza, varities (dry) of apricot etc