The temperature, atmospheric pressure, wind,humidity and precipitation usually determine the weather conditions at any point of time (a day or a week) and the space. Weather is generally expressed as cool, hot, windy, calm, cloudy, bright, wet or dry. Actually, atmospheric conditions are called the weather. We experience hot weather in summers, cold weather in winters, wet weather in rainy season and cool and dry during October-November and the March and April respectively.

Weather phenomenon changes rapidly. Any day may have different weather conditions. We just feel suffocated due to humidity and scorching heat of July month. Suddenly clear sky is covered with clouds and it starts raining with lightning and strong wind. Something of such strange happens when cyclonic depression cause damages in deltas of the Mahanadi, Kaveri, Godavari and Krishna rivers.

Following are the characteristics of the cold season.

(i) It begins from mid-November in Northern India and pervades here till February. The mid-months, i.e., December and January are the coldest months.

(ii) The temperature gradually decreases during this period from south to the north. For example, in Chennai 20°-25°C while it is 10°15°C in northern plains.

(iii) Days are experienced warm while the nights are cold. Days are cut short while nights are longer.

(iv) Most part of the country remains dry (i.e., without winter rain) during this period and only Tamil Nadu coast including Coromandel coast receive heavy winter rains.

(v) Coastal areas enjoy moderate temperature throughout the year while the rest of the country experiences cold, heat, humid and moderate according to the cycle of the seasonal change. It means reversal of winds or monsoon type climate has more seasonal variations to experience.