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Question
‘Rainfall decreases as one travels up the Ganges Valley.’ Why?
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Solution
A branch of Summer Monsoon from Bay of Bengal moves up the Ganges Valley, it moves westwards along the Himalayas. The lower Ganges Valley receives the rainfall first and the upper Ganges Valley later on. Kolkata has an annual rainfall of 160 cm. As the branch of monsoon moves westward, it gets drier and drier. So it gives less rainfall. Varanasi gets 104 cm. of rainfall, Delhi gets 66 cm of rainfall.
RELATED QUESTIONS
Give a reason for each of the following:
Central Maharashtra gets less rainfall than the coastal area of Maharashtra.
Name the following:
The winds that bring heavy rain to Cherrapunji.
Study the climate data given below and answer the questions that follow:
| Month | Jan | Feb | Mar | Apr | May | June | July | Aug | Sep | Oct | Nov | Dec |
| Temperature in °C |
23.1 | 24.8 | 26.5 | 29.2 | 32 | 32.8 | 33.1 | 32.1 | 30.5 | 29.3 | 28.7 | 26.1 |
| Rainfall cm | 15.3 | 10.1 | 0.3 | 0.1 | 1.3 | 4.5 | 6.1 | 10.2 | 10.5 | 20.1 | 16.8 | 19.0 |
- Calculate the annual rainfall experienced by the station.
- Suggest the name of this station, giving a reason for your answer.
- Name the season during which the rainfall is heaviest.
| Stations | Latitude | Altitude (Metres) | Jan. | Feb. | Mar. | Apr. | May. | Jun. | July. | Aug. | Sep. | Oct. | Nov. | Dec. | Annual Rainfall |
|
Temperature (°C) |
20.5 |
22.7 |
25.2 |
27.1 |
26.7 |
24.2 |
23.0 |
23.0 |
23.1 |
22.9 |
18.9 |
20.2 |
|||
| Bengaluru | 12°58'N | 909 |
|
|
|
||||||||||
| Rainfall (cm) | 0.7 | 0.9 | 1.1 | 4.5 | 10.7 | 7.1 | 11.1 | 13.7 | 16.4 |
15.3 |
6.1 |
1.3 |
88.9 | ||
|
Temperature (°C) |
24.4 |
24.4 |
26.7 |
28.3 |
30.0 |
28.9 |
27.2 |
27.2 |
27.2 |
27.8 |
27.2 |
25.0 |
|||
|
Mumbai |
19° N | 11 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Rainfall (cm) |
0.2 |
0.2 |
– |
– |
1.8 |
50.6 |
61.0 |
36.9 |
26.9 |
4.8 |
1.0 |
– |
183.4 | ||
|
Temperature (°C) |
19.6 |
22.0 |
27.1 |
30.1 |
30.4 |
29.9 |
28.9 |
28.7 |
28.9 |
27.6 |
23.4 |
19.7 |
|||
|
Kolkata |
22°34'N | 6 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Rainfall (cm) |
1.2 |
2.8 |
3.4 |
5.1 |
13.4 |
29.0 |
33.1 |
33.4 |
25.3 |
12.7 |
2.7 |
0.4 |
162.5 | ||
|
Temperature (°C) |
14.4 |
16.7 |
23.3 |
30.0 |
33.3 |
33.3 |
30.0 |
29.4 |
28.9 |
25.6 |
19.4 |
15.6 |
|||
|
Delhi |
29° N | 219 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Rainfall (cm) |
2.5 |
1.5 |
1.3 |
1.0 |
1.8 |
7.4 |
19.3 |
17.8 |
11.9 |
1.3 |
0.2 |
1.0 |
67.0 | ||
|
Temperature (°C) |
16.8 |
19.2 |
26.6 |
29.8 |
33.3 |
33.9 |
31.3 |
29.0 |
20.1 |
27.0 |
20.1 |
14.9 |
|||
|
Jodhpur |
26°18'N | 224 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Rainfall (cm) |
0.5 |
0.6 |
0.3 |
0.3 |
1.0 |
3.1 |
10.8 |
13.1 |
5.7 |
5.7 |
0.2 |
0.2 |
36.6 | ||
|
Temperature (°C) |
24.5 |
25.7 |
27.7 |
30.4 |
33.0 |
32..5 |
31.0 |
30.2 |
29.8 |
28.0 |
25.9 |
24.9 |
|||
|
Chennai |
13°4'N | 7 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Rainfall (cm) |
4.6 |
1.3 |
1.3 |
1.8 |
3.8 |
22.2 |
8.7 |
11.3 |
11.9 |
30.6 |
35.0 |
0.2 |
128.6 | ||
|
Temperature (°C) |
21.5 |
23.9 |
28.3 |
32.7 |
35.5 |
32.0 |
27.7 |
27.3 |
27.9 |
26.7 |
23.1 |
20.7 |
|||
|
Nagpur |
21°9'N | 312 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Rainfall (cm) |
1.1 |
2.3 |
1.7 |
1.6 |
2.1 |
22.2 |
37.6 |
28.6 |
18.5 |
5.5 |
2.0 |
13.9 |
124.2 | ||
|
Temperature (°C) |
9.8 |
11.3 |
15.9 |
18.5 |
19.2 |
20.5 |
21.1 |
20.9 |
20.9 |
17.2 |
13.3 |
10.4 |
|||
|
Shillong |
24°34'N | 1461 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Rainfall (cm) |
1.4 |
2.9 |
5.6 |
14.6 |
29.5 |
47.6 |
35.9 |
34.3 |
30.2 |
18.8 |
3.8 |
1.0 |
225.3 | ||
|
Temperature (°C) |
26.7 |
27.3 |
28.3 |
28.7 |
28.6 |
26.6 |
26.2 |
26.2 |
26.5 |
26.7 |
26.6 |
26.5 |
|||
|
Thiruvananthapuram |
8°29'N | 61 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Rainfall (cm) |
2.3 |
2.1 |
3.7 |
10.6 |
20.8 |
35.6 |
22.3 |
14.6 |
13.8 |
27.3 |
20.6 |
7.5 |
181.2 | ||
|
Temperature (°C) |
−8.5 |
−7.2 |
−0.6 |
6.1 |
10.0 |
14.4 |
17.2 |
16.1 |
12.2 |
6.1 |
0.0 |
−5.6 |
|||
|
Leh |
34°N | 3506 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Rainfall (cm) |
1.0 |
0.8 |
0.8 |
0.5 |
0.5 |
0.5 |
1.3 |
1.3 |
0.8 |
0.5 |
– |
0.5 |
8.5 |
In above Table the average mean monthly temperatures and amounts of rainfall of ten representative stations have been given. It is for you to study on your own and convert them into ‘temperature and rainfall’ graphs. A glance at these visual representations will help you to grasp instantly the similarities and differences between them. One such graph (Figure 1) is already prepared for you. See if you can arrive at some broad generalisations about our diverse climatic conditions. 
Why are there great variations in the climate of the Indian sub-continent?
Why are Himalayas called perfect climate divide? Explain their two-fold functions in this regard.
Equable and Extreme climates.
Study the climatic data given below and answer the questions that follow:
| Month | Jan. | Feb. | Mar. | Apr. | May | Jun. | Jul. | Aug. | Sep. | Oct. | Nov. | Dec. |
| °C | 25.0 | 25.5 | 26.3 | 27.1 | 30.0 | 36.2 | 36.0 | 35.9 | 30.3 | 28.4 | 27.0 | 24.6 |
| cm | 24.5 | 23.1 | 15.0 | 2.4 | 0.1 | 11.0 | 9.3 | 7.2 | 4.0 | 9.4 | 14.5 | 20.4 |
(i) Calculate the annual temperature range.
(ii) What is the total annual rainfall?
(iii) Presuming that the station is located in India, give a reason for its location being on the east coast or the west coast of India.
Name two types of cyclonic systems that affect India and two areas that receive rainfall from these systems.
Explain How is distribution of annual rainfall in related to the relief of the country? with examples.
