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Question
What are ‘Western Disturbances’?
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Solution
Western Disturbances are cyclonic systems originating in the Mediterranean region that travel eastward towards the Indian subcontinent, particularly during the winter months. These disturbances are caused by the movement of westerly winds in the upper atmosphere, also known as the westerly jet stream.
RELATED QUESTIONS
Give a reason for each of the following:
The Summer Monsoon winds blow over the Arabian Sea from the South West.
Mention the geographical reason for the following:
Western Rajasthan receives no rain from the Arabian Sea branch of the South West Monsoon winds.
Give an account of weather conditions and characteristics of the cold season.
| 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. 
Which type of climate is experienced in the Northern Plains of India? State one main characteristic of this type of climate.
When the Malabar coast is receiving heavy rainfall in July, the Tamil Nadu coast is comparatively dry.
Thar Desert gets very little rain.
Give reason why Shillong gets hardly 200 cm., rainfall during the year, whereas Cherrapunji gets more than 1250 cm, of rainfall although they are situated very close to each other.
Name two types of cyclonic systems that affect India and two areas that receive rainfall from these systems.
Study the climate data of Station X and answer the questions that follow:
| Month | Jan. | Feb. | Mar. | Apr. | May | June | July | Aug. | Sep. | Oct. | Nov. | Dec. |
| Temperature °C | 21.0 | 21.9 | 24.3 | 27.2 | 28.0 | 26.4 | 26.1 | 25.4 | 26.0 | 26.0 | 23.8 | 21.2 |
| Rainfall in cm | 5.1 | 2.8 | 1.2 | 1.7 | 3.9 | 4.6 | 8.4 | 11.4 | 11.9 | 31.6 | 34.5 | 14.8 |
- Calculate the annual range of temperature of Station X.
- Name the wind that brings most of the rainfall to this station.
- On which coast of India is Station X located?
