This region covers the northern Himalayan region extending from the west (better the north-south flow of the Sindh), through Jammu and Kashmir, the Himalayan Parallel ranges to the north-east of India.
The Karakoram which is an older area than the Himalayas is also accommodated in this region.
Climatic variations arc due to the following reasons:
This region has a very long longitudinal extent from 72° to 92°E. Though latitudinal spread is not much, yet the altitudinal variations put the effect of latitudinal variations in the background.
Mount Everest (8848 m) at the top and the Siwaliks at the foot make climatic variations greatly pronounced. The tropical climate at the foot contrasts with the polar type of climate atsnowelad mountain ranges of the Himalayas.
The fall of temperature is about 0-6°C per 100 metres. Temperature inversions in the valleys bring about a contrast of climate especially at higher altitudes. The S.W Monsoon strikes the Himalayas in the east and the main branch moves along the Himalayas towards west with decreasing amount of rainfall.
The incursion of cyclones, depressions, etc. from the Mediterranean Sea and the Gulf of Oman, their frequency and the variability in their routes produce a sudden change in the climate, bringing snowfall, rainfall, etc.
(A) The Main Himalayan Belt
This Himalayan belt is exposed from the south to S.W Monsoons and receives a lot of rainfall but the norths of its slopes are in the leeward situation and get very low rainfall. For example, the southern slopes get 100-300 cm rain while on the northern slope the average rainfall is 20-40 cm.
The heavy rainfall on the southern slope ranges between 250-300 cm at heights between 1000 to 2500 m above sea level. For example, Dharamsala in Himachal Pradesh gets about 300 cm of rainfall.
However, rainfall decreases above 2200 m. Shimla’s rainfall is around 150 cm and Srinagar behind Pir Panjal ranges gets hardly 70 cm.
The rainfall has another mode of variation. It decreases from the cast to the west. Darjeeling in the cast gets 320 cm and Mussooric towards west gets about 220 cm.
In summer the temperatures in the Himalayas arc very comfortable. Even in June the temperature at Shimla at a height of2205 metres is around 20°C which is, however, near about the same as that at Dharamsala and other hill stations.
The Himalayas therefore, naturally attract tourists from the smouldering plains and hot south. In winter the temperature falls below freezing point.
The winter rain of the Himalayas is lower than that in summer because it is due to western disturbances. Snowfall is common above 1500 metres of height from the sea level. The rainfall in the winter ranges from 25 cm to 50 cm.
It is not suitable to live above 3000 metres because of the low percentage of oxygen in the atmosphere.
(B) The Trans-Himalayan Region
This area lies on the north of the Himalayan ranges. It is very different from the main Himalayan ranges.lt is beyond the influence of humid monsoon winds which can’t reach there on account of the high Himalayan altitude.
It is important to note that the rainfall is extremely low in the trans-Himalayas. Leh jjets 8-2 cm while Skardu gets about 16 cm and that too in the form of snow.
This has made them cold deserts. The temperature in January is about 8°C below freezing point and even in July it is around -1-7°C. Skardu’s temperature is -6-5°C almost as low as that of Leh.
Pine and Deodars are common trees around 1800-2000 m. but above 3,500 m grasslands predominate and then permanent snow, caps the higher mountain ranges. Coniferous forests in the lower parts are a rich growh for different uses.
Tropical deciduous forests grow upto 1500 m. in the west but evergreen rain forests occur towards the rainier east. Shorea Robusta or Sal flourishes even where rainfall is high but there must be a dry season during the year.
Towards east in the lower areas (1000 m) tropical evergreen forests are found. Steppe forests grow extensively in the north-west where rainfall is low.