Our Revision Notes for GSEB Class 9 Social Science Notes Chapter 16 Climate summarises the key points of a chapter and useful resource to prepare effectively for the upcoming board exams.

Climate Class 9 GSEB Notes Social Science Chapter 16

Climate Class 9 GSEB Notes

→ Climate is an average of atmospheric conditions over a long period.

→ Weather is an average of short term conditions of atmosphere.

→ The winds which change their direction according to the season are called ‘Monsoon winds’.

→ These winds are so named after the Arabic word ‘Mausim’.

→ Seasons are caused due to the axial tilt.

→ Regions receiving more sun light experience summer while regions receiving less sun light experience winter.

→ Rotation and revolution of the earth have a direct impact on the food, clothing and residences of man.

→ South India has a peninsular shape, hence it experiences moderate maritime climate, while the climate becomes more continental while going away from the sea shore.

→ A large part of North India is away from the sea coast so it experiences continental climate.

Factors affecting the climate : The climate of India :
→ Latitude : Climate type on the surface of the earth changes according to the latitude of the place concerned.

→ Distance from sea: Water and land have different capacity to conserve and release the solar heat.

→ Asa result, coastal regions experience temperature climate, while the climate becomes continental in the interior places away from sea coast.

→ Altitude: As we go higher in the atmosphere from sea level, air pressure and air temperature decreases, while higher relief gets more rain.

→ Due to the high altitude, the Himalayan peaks remain snow covered throughout the year.

→ Atmospheric pressure and winds: During winter, high pressure develops to the north of Himalayas.

→ Cold and dry winds from this region blow towards the oceanic area where low pressure is created.

→ During summer, low pressure develops due to high temperature over central Asia and Indian landmass.

→ Phenomena like Jet Stream, Western Disturbances, El- Nino, I.T.C.Z. have affected the Indian weather to a great extent.

Seasons of India :
→ India Meteorological Department of Government of India at Delhi has divided the climate of India into four seasons : Winter, Summer, Rainy season, Retreating Monsoon season.

Cold Weather season – Winter (December to February)

• In India, the three months’ duration from December to February is considered as winter.
• North-East India remains comparatively cooler as it is far away from the sea and some part of it is a desert.
• In this season temperature decreases suddenly.
• Frost in some area destructs the cotton crop.
• Temperature does not fall below freezing point during winter except for the high mountainous regions.
• South India is situated in torrid zone, near the equator and has a peninsular shape.
• Its inner area is not very far from sea coast.
• So this area does not feel severe cold as the Northern India during winter.
• There is no snowfall.
• Day is shorter and night is longer.

Warm Weather season – summer (Grishma season)

• In Indian the warm and dry season between March to May is called ‘Summer’.
• During this period the sun rays fall vertically from south to north gradually and the landmass becomes warmer.
• Temperature increases continuously.
• Due to the altitude of peninsula and the plateau, the summer in south India is little mild.

The Advancing Monsoon (Rainy season – June to September)

• About 80% of the rainfall country is received between June to September.
• India farmer is busy in farming from the beginning of the rainy season.
• South-West monsoon winds are responsible for the rain in this season and the humid and cloudy weather.
• Due to the peninsular shape of South India, the South-West monsoon winds are divided into two parts:
  (1) Arabian Sea Current, and
  (2) Bay of Bengal Current.

Arabian Sea Current

• Rain decreases northwards from Kerala to Karnataka, Goa and Maharashtra on western coast.
• One branch of this current enters Madhya Pradesh through the Narmada valley.
• This current further merges with the winds coming over from Bay of Bengal.

Bay of Bengal Current

• Second branch of the south – west monsoon winds first enters West Bengal and then reaches
  up to Meghalaya.
• These winds contain maximum moisture which give heavy rain in Meghalaya.
• ‘Rain Break’ is associated with the monsoon winds.
• The monsoon rain falls for many days.

Retreating Monsoon (October – November)

• Duration between October and November is better known as Retreating Monsoon.
• When the pressure conditions change afterwards, these winds start flowing back towards the sea during October – November.
• So this period is called season of ‘Retreating Monsoon’.

Climate and Human Life

• Irregularity and uncertainty are its characteristics which have a profound impact on climate and the food, life style, nature of people agriculture.
• Due to high temperature during most of the year in India, a large variety of crops can be cultivated.