Q- Give an account of weather conditions and characteristics of the cold season.
Answer- India is a large country which has various weather conditions. Some of them are as follows:
1. The differential heating and cooling of land and water creates low pressure on the landmarks of India while the seas around experience comparatively high pressure.
2. The western Jet stream moves to the north of the Himalayas, and the tropical easterly jet stream moves over the Indian peninsula during summer.
3. The periodic change in pressure conditions between Pacific Ocean and the Indian Ocean, also known as the ‘Southern Oscillation’ or ‘SO’ also affects the monsoon.
4. The Tibetan plateau get intensely heated during summer. This leads in strong vertical air currents and formation of high pressure mover the plateau. This high pressure zone is about 9 Km above the sea level.
5. The high pressure areas, east of the Madagascar is approximately 20°S over the Indian Ocean. This area affects the Indian monsoon.
6. The Inter Tropical Convergence Zone (ITCZ) is normally positioned about 5°N of the equator. During summer, it shifts over the Ganga plains. It is also known as the monsoon trough during the monsoon season.
7. The difference in pressure over Tahiti and Darwin is computed to predict the intensity of the monsoons. Tahiti (18°S/149°W) lies in the Pacific Ocean and Darwin (12°30ˊS/131°E) lies in the northern Australia. If the pressure differences are negative, it means a below average and late monsoon.
The main characteristics of cold season are as follows:
1. The winter season starts or begins from mid-November and continues till February in the Northern Plains.
2. The most cold months in Northern Plains are December and January.
3. At various region of India the days are too hot and nights are too cold in winter season. For example: Thar Desert of Rajasthan had such climate that the days are too hot and nights are too cold.
4. The weather is usually marked by clear sky, low temperature and low humidity and low variable winds.
5. The winter rainfall is in small amount but is very important for the rabi crop. The rainfall is locally known as mahawat.