RBSE Class 9 Social Science Notes Geography Chapter 4 Climate

These comprehensive RBSE Class 9 Social Science Notes Geography Chapter 4 Climate will give a brief overview of all the concepts.

RBSE Class 9 Social Science Notes Geography Chapter 4 Climate

→ Climate:
Climate refers to the stun total of weather conditions and variations over a large area for more than thirty years.

→ Weather:
Weather refers to the state of the atmosphere over an area at any point of time.

→ Climate of India:
The dimate of India is described as the ‘monsoon’ type. Most parts of the country receive rainfall from June to September.

→ Climatic Controls:
There are six major controls of the climate of any place. They are-

1. latitude,
2. altitude,
3. pressure and wind system,
4. distance from the sea (continentality),
5. ocean currents and
6. relief features.

→ Factors Affecting India’s Climate:

• Latitude: The Tropic of Cancer passes through the middle of the country. Therefore, India’s climate has characteristics of tropical as well as subtropical climates.
• Altitude: India has mountains to the north, which have an average height of about 6,000 metres. The Himalayas preveiit the cold winds from Central Asia from entering the subcontinent.
• Pressure and Winds: The pressure and wind conditions over India are unique. Here, the dimate and assodated weather conditions in India are governed by the following atmospheric conditions:
  (a) Pressure and surface winds
  (b) Upper air drculation; and
  (c) Western cydonic disturbances and tropical cyclones.

→ Coriolis force:
An apparent force caused by the earth’s rotation. The Coriolis force is responsible for deflecting winds towards the right in the northern hemisphere and towards the left in the southern hemisphere.

→ Jet stream:
These are a narrow belt of high altitude (above 12,000 m) westerly winds in the troposphere. Their speed varies from about 110 km/h in summer to about 184 km/h in winter. These jet streams are located approximately over 27°-30° north latitude, therefore, they are known as subtropical westerly jet streams.

→ The Onset of the Monsoon and Withdrawal:

• The dimate of India is strongly influenced by monsoon winds. The monsoons are experienced in the tropical area roughly between 20° N and 20° S. The monsoon period lasts from early June to mid- September. The monsoon arrives at the southern tip of the Indian peninsula generally by the first week of June. By mid-July, the monsoon reaches in the rest of the country.
• The withdrawal of the monsoon begins by early September. By early December, the monsoon withdraws from the rest of the country.

→ The Seasons: Four main seasons can be identified in India:

• The cold weather season,
• The hot weather season,
• The advancing monsoon and
• The retreating monsoon with some regional variations.

The cold weather season begins from mid-November in northern India and stays till February. As such, from March to May, it is hot weather season in India. Monsoon arrives in the country from the beginning of June. The months of October-November form a period of transition from hot rainy season to dry winter conditions.

→ Distribution of Rainfall:
The distribution of rainfall in India is very uneven. Where there is 400 cm of rain in Meghalaya, it is less than 60 cm in Ladakh and western Rajasthan.