NCERT Book Class 11 Geography Climate

CLIMATE

We drink more water during summers. Your uniform during the summer is different from the winters. Why do you wear lighter clothes during summers and heavy woollen clothes during winters in north India? In southern India, woollen clothes are not required. In northeastern states, winters are mild except in the hills. There are variations  in weather conditions during different seasons.These changes occur due to the changes in the  elements of weather (temperature, pressure, wind direction and velocity, humidity and precipitation, etc.).

UNITY AND DIVERSITY IN THE MONSOON CLIMATE

The monsoon regime emphasises the unity of India with the rest of southeast Asian region. This view of broad unity of the monsoon type of climate should not, however, lead one to ignore its regional variations which differentiate the weather and climate of different regions of India. For example, the climate of Kerala and Tamil Nadu in the south are so different from that of Uttar Pradesh and Bihar in the north, and yet all of these have a monsoon type of climate. The climate of India has many regional variations expressed in the pattern of winds, temperature and rainfall, rhythm of seasons and the degree of wetness or dryness. These regional diversities may be described as sub-types of monsoon climate.

Let us take a closer look at these regional variations in temperature, winds and rainfall. While in the summer the mercury occasionally touches 55°C in the western Rajasthan, it drops down to as low as minus 45°C in winter around Leh. Churu in Rajasthan may record a temperature of 50°C or more on a June day while the mercury hardly touches 19°C in Tawang (Arunachal Pradesh) on the same day. On a December night, temperature in Drass (Jammu and Kashmir) may drop down to minus 45°C while Tiruvanantapuram or Chennai on the same night records 20°C or  22°C. These examples confirm that there are seasonal variations in temperature from placeto place and from region to region in India. Not only this, if we take only a single place and record the temperature for just one day, variations are no less striking. In Kerala and in the Andaman Islands, the difference between day and night temperatures may be hardly seven or eight degree Celsius. But in the Thar desert, if the day temperature is around 50°C, at night, it may drop down considerably upto 15°-20°C.

FACTORS DETERMINING THE CLIMATE OF INDIA

India’s climate is controlled by a number of factors which can be broadly divided into two groups — factors related to location and relief, and factors related to air pressure and winds. Factors related to Location and Relief Latitude : You already know the latitudinal and longitudinal extent of the land of India. You also know that the Tropic of Cancer passes through the central part of India in east-westdirection. Thus, northern part of the India lies in sub-tropical and temperate zone and the part lying south of the Tropic of Cancer falls in the tropical zone. The tropical zone being nearer to the equator, experiences high temperatures throughout the year with small daily and annual range. 

Exercise

1. Choose the right answer from the four alternatives given below.

(i) What causes rainfall on the coastal areas of Tamil Nadu in the beginning of winters?

    (a) South-West monsoon

    (b) North-Eastern monsoon

    (c) Temperate cyclones

    (e) Local air circulation

(ii) What is the proportion of area of India which receives annual rainfall less than 75 cm?

     (a) Half

     (b) Two-third

     (c) One-third

     (d) Three-fourth

(iii) Which one of the following is not a fact regarding South India?

     (a) Diurnal range of temperature is less here.

     (b) Annual range of temperature is less here.

     (c) Temperatures here are high throughout the year.

     (d) Extreme climatic conditions are found here.

(iv) Which one of the following phenomenon happens when the sun shines vertically over the Tropic of Capricorn in the southern hemisphere?

     (a) High pressure develops over North-western India due to low temperatures.

     (b) Low pressure develops over North-western India due to high temperatures.

     (c) No changes in temperature and pressure occur in north-western India.

     (d) ‘Loo’ blows in the North-western India.

(v) In which of the following states in India do we find ‘As’ type of climate as per Koeppen’s classification?

     (a) In Kerala and coastal Karnataka

     (b) In Andaman and Nicobar Islands

     (c) On Coromandal coast

     (d) In Assam and Arunachal Pradesh

EXERCISES

 Answer the following questions in about 30 words.

(i) What are the three important factors which influence the mechanism of Indian weather?

(ii) What is the Inter-Tropical Convergene Zone?

(iii) What is meant by ‘bursting of monsoon’? Name the place of India which gets the highest rainfall.

(iv) Define ‘climatic region’? What are the bases of Koeppen’s classification?

(v) Which type(s) of cyclones cause rainfall in north-western India during winter? Where do they originate?

Answer the following questions in not more than 125 words.

(i) Notwithstanding the broad climatic unity, the climate of India has many regional variations. Elaborate this statement giving suitable examples.

(ii) How many distinct seasons are found in India as per the Indian Meteorological Department? Discuss the weather conditions associated with any one season in detail.

Project/Activity

On the outline map of India, show the following:

(i) Areas of winter rain

(ii) Wind direction during the summer season

(iii) Areas having variability of rainfall over 50 per cent

(iv) Areas having less than 15°C temperature in January

(v) Isohyte of 100 cm.

Please refer to attached file for NCERT Class 11 Geography Climate