Spatial and temporal distribution of temperature & pressure

  • Surface Pressure and Winds In winter months, are generally influenced by the distribution of pressure in Central and Western Asia.
  • A high pressure centre in the region lying to the north of the Himalayas develops during winter. This centre of high pressure gives rise to the flow of air at the low level from the north towards the Indian subcontinent, south of the mountain range.
  • The surface winds blowing out of the high pressure centre over Central Asia reach India in the form of a dry continental air mass.
  • These continental winds come in contact with trade winds over northwestern India.
  • Jet Stream and Upper Air Circulation Higher up in the lower troposphere, about three km above the surface of the earth, a different pattern of air circulation is observed.
  • All Of WesternandCentral Asia remains under the influence of westerly winds along the altitude of 9-13 km from west to east.
  • These winds blow across the Asian continent at latitudes north of the Himalayas roughly parallel to the Tibetan highlands
  • These are known as jet streams. Tibetan highlands act as a barrier in the path of these jet streams. As a result, jet streams get bifurcated. One of its branches blows to the north of the Tibetan highlands, while the southern branch blows in an eastward direction, south of the Himalayas.
  • Western Cyclonic Disturbance and Tropical Cyclones enter the Indian subcontinent from the west and the northwest during the winter months, originate over the Mediterranean Sea and are brought into India by the westerly jet stream.


isobars in January


isotherms in january