Class 9 NCERT CBSE, Social Science (Geography)
Contemporary India – I, Chapter-14, CLIMATE
Solution of Q.1:
(i) The bulk of rainfall in India is concentrated over a few months starting from June to September. Because, during these four months, the rain-bearing winds called the South-West Monsoons, blow northwards in two streams from the Arabian Sea and the Bay of Bengal. These winds blow from the oceanic high pressure areas towards the low pressure areas of land and make a heavy rainfall.
Winds blowing from the Arabian Sea cause heavy rainfall exceeding 300 cm along the Western Ghats. Winds blowing from the Bay of Bengal cause heavy rainfall in the hills of Assam, Meghalaya, Mawsynram.
(ii) In winter there is a high pressure on the Indian mainland while the pressure over the Indian Ocean remains low then. So, winds start blowing from Indian mainland towards the sea in winter. These winds are called retreating monsoons which blow in the months of October and November from the land towards the sea from northeast direction.
When these dry winds cross over the Bay of Bengal, they pick up moisture and when they strike against the Eastern Ghats they cause heavy rain on the east coast of India. Hence, southern part of east coast of India or the Tamil Nadu coast receives more rain during the winter months from October to November.
(iii) In India a gradual climatic transition from hot rainy season to dry winter season takes place during the months of October and November. In the later half of October, temperature starts falling rapidly especially in North India and the low pressure conditions starts shifting towards the Bay of Bengal by November. This shift causes cyclonic depression in the Andaman Sea. These tropical cyclones cause heavy and wide-spread rains on the Eastern Coasts of India. so they often become destructive and the densely populated deltas of the Godavari, the Krishna, the Kaveri are frequently struck by these cyclones causing heavy damage to life and property every year.
(iv) Drought in Rajasthan and Gujarat: There is often low rain in Rajasthan (Thar Desert) and Gujarat because there is no relief or obstruction here to check the monsoons coming from the Arabian Sea. The Aravalli Hills lie parallel to the direction of the monsoons as such the monsoons bypass Rajasthan and Gujarat unobstructed and so, without giving any rain. Moreover, in the summer the temperature of the Thar Dessert or Western Rajasthan is so high that the monsoon winds that pass over this region get dried and unable to cause any rain.
Drought in the Leeward side of Western Ghats: There is often low rainfall in the Leeward side of Western Ghats because that area comes under the rain shadow area.
Solution of Q.2:
Equable Climate: Equable climate is one which is neither too hot in summer nor too cold in winter. The coastal regions, influenced by the cool sea breeze are known for their equable or moderate climate. Hence the climate of coastal regions is known as Equable Climate.
Solution of Q.3:
Extreme Climate: The climate in which the summer is extremely hot and winter is too much cold, is known as Extreme Climate, also known as Continentality. This type of climate is found in the arid regions of Rajasthan, South-west Punjab.
Continentality increases with increase in distance of a place from sea.
Solution of Q.4:
Rain Shadow: That side of the mountain which does not get much rain is known as rain shadow. The winds after crossing the summits of the mountains descend along the slopes on the other side of the mountains. During this process the descending winds get warmed up and dry. The other reason is that the moist wind may not cross over the other side of the mountains which are too high as is the case with the Himalayas which render Tibet as dry region.
Solution of Q.5:
The basic elements of both weather and climate are same –
- winds and
- cloudiness or sunshine
Solution of Q.6:
Solution of Q.7:
Thar Dessert in Rajasthan.
Solution of Q.8:
Solution of Q.9:
Jet Streams: Jet Streams are fast blowing westerly winds that blow in a narrow zone in high altitudes of above 1200 meter in the troposphere. A number of separate Jet streams have been identified with their speeds varying from 110 km/hr to 184 km/hr.
Solution of Q.10:
The cyclonic disturbances affecting the coastal belts of Odisha and Andhra Pradesh occur due to the tropical cyclones during the monsoons as well as in Oct – Nov.
During monsoons theses disturbances are caused by tropical cyclones which are a part of easterly flow.
During Oct – Nov with the apparent movement of Sun towards the South, the low pressure trough, over the Northern plains, is shifted towards the Bay of Bengal. This shift is associated with occurrence of cyclonic depressions which originated over the Andaman Sea. These cyclones while crossing the Eastern Coasts cause heavy and wide-spread rainfall. Sometimes these tropical cyclones arrive at the coasts of Odisha, Andhra, West Bengal and Bangladesh and cause great danger to life and property.
Solution of Q.11:
Take hint from the answer of the Q.1(ii).
Solution of Q.12:
Loo: These are strong, gusty, hot, dry winds blowing during a day over the North and North-Western India. Direct exposure to these winds may even prove to be fatal.
Kaal Baisakhi: During the months of April and May the localized thunderstorms associated with violent winds, torrential rains often accompanied by hail are known as the Kaal Baisakhi. This term is more popular in West Bengal.
Mango Shower: Towards the close of the summer season, pre-monsoon showers are common especially, in Kerala and Karnataka. They help in early ripening of mangoes, and are often referred to “mango showers”.
Mahawat: The total amount of rainfall over Northern plains during winter is locally known as ‘Mahawat’. It is important for the cultivation of the Rabi crops.
Further study: CBSE Class 9 NCERT solutions for Geography