Social Science 3 Marks Each

Along with monsoon winds, cyclones originating over Bay of Bengal and Arabian Sea also enter India. Due to this monsoon becomes more active in some areas. These cyclones help in bringing rainfall.
The monsoon rainfalls for many days. But there are a few rainless days and again it is followed by a spell of rain. This phenomenon is called ‘Rain Break’.
Thus, all these factors affect the distribution of rainfall. Assam and Meghalaya receive very heavy rainfall while the deserts in Rajasthan and Leh in Kashmir receive insignificant rain.
These factors have made the amount and distribution of rainfall unequal in India.

This is a Spanish word which literally means a ‘small child’.
The name was given by Peruvian fishermen after the child Jesus because its impact is generally felt around Christmas.
El-Nino is a warm current originates to the west of Peru along the Pacific coast in South America due to atmospheric and oceanic conditions. This current flows eastwards and its impact is felt up to India.
The El-Nino phenomena takes place occasionally.
Whenever El-Nino takes place, changes occur in the duration of monsoon and amount of rainfall in India.

It is located far from the sea and its some part of region is a desert.
During winter this region develops high pressure and cool and dry winds are generated. Due to that direction of wind is also changed. Wherever these winds reach, temperature decreases there.
During winter temperature does not fall below freezing point except for the high mountainous regions, because the Central Himalayas obstruct the extremely cold winds coming from Central Asia, protects northern Indian from severe cold.
After the snowfall in Himalayas, the cold and heavy winds rush towards the North Indian plains. So, temperature decreases. Frost is found in some areas. Moreover, temperature remains very low in Himalayas, e.g. in January temperature of Shimla and Darjeeling is around 5°C.

• The permanent winds blowing from Tropical high pressure belts in both hemispheres towards the Equatorial low pressure belt are called‘Trade Winds’.
• These winds deflect slightly due to the coriolis force and blow towards equator. These winds blow regularly at almost uniform velocity. They used to be beneficial earlier to the ships run on wind energy on sea routes for trade. Since then these winds are known as ‘Trade Winds’.
• As these winds blow from land these are dry. But when they pass over the vast water mass of the Indian Ocean in the south, the Arabian Sea in the west and the Bay of Bengal in the east, they bring much moisture and give rain in India.

• Height from sea level: The temperature and the pressure of the atmosphere decrease as we go higher from sea level. Generally the temperature decreases by 1°C for every 165 metres or by 6.5°C for every 1000 metres.
• Every layer of the air exerts pressure over the underlying layer. As we go higher the air layers are less in number and thin, so the pressure decreases. That is why the air re cool in higher mountainous regions. is much heat in the plains of north Gujrat while the hill station at Mt. Abu, which nearby, enjoys pleasant weather during summer.
• Altitude increases the rainfall. Very high peaks of Himalaya remain snow-clad throughout the year. As the damp air rises high and cools down, it gives rain. e.g., In the mountainous regions of Assam and Meghalaya, there is more rain with the increase in height.