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 10
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.