NCERT Book Class 9 Social Science (Geography) Chapter 4 Climate

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C LIMATE

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n the last two chapters you have read about The climate of India is described as the
the landforms and the drainage of ‘monsoon’ type. In Asia, this type of climate
our country. These are the two of the three is found mainly in the south and the southeast.
basic elements that one learns about the natural Despite an overall unity in the general pattern,
environment of any area. In this chapter you there are perceptible regional variations in
will learn about the third, that is, the climatic conditions within the country. Let us
atmospheric conditions that prevail over our take two important elements – temperature and
country. Why do we wear woollens in December precipitation, and examine how they vary from
or why it is hot and uncomfortable in the month place to place and season to season.
of May, and why it rains in June - July? The In summer, the mercury occasionally
answers to all these questions can be found out touches 50°C in some parts of the Rajasthan
by studying about the climate of India. desert, whereas it may be around 20°C in
Climate refers to the sum total of weather Pahalgam in Jammu and Kashmir. On a winter
conditions and variations over a large area for night, temperature at Drass in Jammu and
a long period of time (more than thirty years). Kashmir may be as low as minus 45°C.
Weather refers to the state of the atmosphere Thiruvananthapuram, on the other hand, may
over an area at any point of time. The elements have a temperature of 22°C.
of weather and climate are the same, i.e.
temperature, atmospheric pressure, wind, In certain places there is a
wide difference between day and night
humidity and precipitation. You may have
temperatures. In the Thar Desert the day
observed that the weather conditions fluctuate temperature may rise to 50°C, and drop down
very often even within a day. But there is some to near 15°C the same night. On the other hand,
common pattern over a few weeks or months, there is hardly any difference in day and night
i.e. days are cool or hot, windy or calm, cloudy temperatures in the Andaman and Nicobar
islands or in Kerala.
or bright, and wet or dry. On the basis of the
generalised monthly atmospheric conditions,
Let us now look at precipitation. There are
the year is divided into seasons such as winter,
variations not only in the form and types of
summer or rainy seasons.
The world is divided into a number of precipitation but also in its amount and the
climatic regions. Do you know what type of seasonal distribution. While precipitation is
climate India has and why it is so? We will mostly in the form of snowfall in the upper parts
learn about it in this chapter. of Himalayas, it rains over the rest of the
country. The annual precipitation varies from
• The word monsoon is over 400 cm in Meghalaya to less than 10 cm
derived from the Arabic word ‘mausim’ which
literally means season. in Ladakh and western Rajasthan. Most parts
• ‘Monsoon’ refers to the seasonal reversal in the of the country receive rainfall from June to
wind direction during a year. September. But some parts like the Tamil Nadu