During winter, the sun is overhead in the Tropic of Capricorn. The land mass becomes cold in North India where the day mean temperature remains below 21 degree Celsius and the night temperature is about 22 degree Celsius. No obvious difference is found in the temperature during day and night.
In the meantime high pressure develops in the northwestern part of India because of prevalence of low-temperature. In contrast to this, a low pressure area forms in the South India, that is both in the Arabian Sea and the Bay of Bengal. Consequently the winds blow from the high pressure area towards South India. These winds are called theRetreating monsoon windswhich blow from land to sea and do not cause much rainfall. But these winds absorb some moisture while crossing the Bay of Bengal and gives winter rainfall to Tamil Nadu and South Andhra Pradesh.
Main Characteristics of Retreating Monsoon
(i) October and November are the months of retreating monsoon.
(ii) During this season low monsoon trough becomes weak and is replaced by high pressure. Thus, monsoon begins to retreat. By the beginning of October it retreats completely from Northern Plains.
(iii) This period is the period of transition from hot rainy season to cold winter season. It is marked by clear sky, moist ground and high temperatures giving birth to October Heat.
(iv) Low pressure trough shifts to Bay of Bengal. They give rise to cyclonic depressions which cause havoc on the eastern coasts-especially the coasts of Orissa, Andhra Pradesh and Tamil Nadu with very strong storms and rains. The super cyclone of 1999 will remain in the memories of millions of people for over, who lost their near and dear ones along with their properties.
