Climate Class 9 Geography NCERT
Detailed notes
Definitions
Climate: Sum total of weather conditions and variations over a large area for more than 30 years.
Weather: State of the atmosphere over an area at any point in time.
Elements of Weather and Climate:
Temperature
Atmospheric pressure
Wind
Humidity
Precipitation
Seasonal Patterns
Weather conditions can fluctuate frequently, but common patterns emerge over weeks or months.
Year is divided into seasons: winter, summer, rainy.
Climatic Regions
The world is divided into various climatic regions.
India has a monsoon climate, primarily found in the south and southeast of Asia.
Regional variations exist in climatic conditions across India.
Temperature Variations
Summer temperatures can reach up to 50°C in Rajasthan desert.
Pahalgam (Jammu and Kashmir) may have temperatures around 20°C in summer.
Winter temperatures can drop to -45°C in Drass (Jammu and Kashmir).
Thiruvananthapuram may have winter temperatures around 22°C.
Precipitation Variations
Types and amounts of precipitation vary across regions:
Snowfall in the Himalayas.
Rainfall in other parts of the country.
Annual precipitation ranges from:
Over 400 cm in Meghalaya.
Less than 10 cm in Ladakh and western Rajasthan.
Most rainfall occurs from June to September; Tamil Nadu coast receives rain mainly in October and November.
, Temperature and Rainfall Contrasts
Coastal areas experience less temperature contrast.
Greater seasonal contrasts are found in the interior regions.
Rainfall generally decreases from east to west in the Northern Plains.
Impact on Lifestyle
Variations in climate affect:
Food habits
Clothing choices
Types of housing
Temperature Variations
In the Thar Desert:
Day temperature can reach 50°C.
Night temperature can drop to around 15°C.
In Andaman and Nicobar Islands and Kerala:
Little to no difference in day and night temperatures.
Climatic Controls
Six major controls of climate:
1. Latitude- Solar energy varies with latitude; temperature decreases from equator to poles.
2. Altitude- Temperature decreases with altitude; higher altitudes are cooler.
3. Pressure and Wind System- Influenced by latitude and altitude, affecting temperature and rainfall patterns.
4. Distance from the Sea (Continentality)- Sea moderates climate; greater distance leads to extreme weather conditions
(hot summers, cold winters).
5. Ocean Currents- Warm or cold currents affect coastal climate through onshore winds.
6. Relief Features- High mountains act as barriers for winds and can cause precipitation; leeward sides tend to be dry.
Factors Affecting India’s Climate
Latitude
The Tropic of Cancer runs through India from Rann of Kuchchh (west) to Mizoram (east).
Half of India lies south of the Tropic, classified as tropical; the northern half is subtropical.
Altitude
Northern mountains average about 6,000 meters in height.
Coastal areas have a maximum elevation of about 30 meters.
The Himalayas block cold winds from Central Asia, resulting in milder winters compared to Central Asia.
Pressure and Winds
Detailed notes
Definitions
Climate: Sum total of weather conditions and variations over a large area for more than 30 years.
Weather: State of the atmosphere over an area at any point in time.
Elements of Weather and Climate:
Temperature
Atmospheric pressure
Wind
Humidity
Precipitation
Seasonal Patterns
Weather conditions can fluctuate frequently, but common patterns emerge over weeks or months.
Year is divided into seasons: winter, summer, rainy.
Climatic Regions
The world is divided into various climatic regions.
India has a monsoon climate, primarily found in the south and southeast of Asia.
Regional variations exist in climatic conditions across India.
Temperature Variations
Summer temperatures can reach up to 50°C in Rajasthan desert.
Pahalgam (Jammu and Kashmir) may have temperatures around 20°C in summer.
Winter temperatures can drop to -45°C in Drass (Jammu and Kashmir).
Thiruvananthapuram may have winter temperatures around 22°C.
Precipitation Variations
Types and amounts of precipitation vary across regions:
Snowfall in the Himalayas.
Rainfall in other parts of the country.
Annual precipitation ranges from:
Over 400 cm in Meghalaya.
Less than 10 cm in Ladakh and western Rajasthan.
Most rainfall occurs from June to September; Tamil Nadu coast receives rain mainly in October and November.
, Temperature and Rainfall Contrasts
Coastal areas experience less temperature contrast.
Greater seasonal contrasts are found in the interior regions.
Rainfall generally decreases from east to west in the Northern Plains.
Impact on Lifestyle
Variations in climate affect:
Food habits
Clothing choices
Types of housing
Temperature Variations
In the Thar Desert:
Day temperature can reach 50°C.
Night temperature can drop to around 15°C.
In Andaman and Nicobar Islands and Kerala:
Little to no difference in day and night temperatures.
Climatic Controls
Six major controls of climate:
1. Latitude- Solar energy varies with latitude; temperature decreases from equator to poles.
2. Altitude- Temperature decreases with altitude; higher altitudes are cooler.
3. Pressure and Wind System- Influenced by latitude and altitude, affecting temperature and rainfall patterns.
4. Distance from the Sea (Continentality)- Sea moderates climate; greater distance leads to extreme weather conditions
(hot summers, cold winters).
5. Ocean Currents- Warm or cold currents affect coastal climate through onshore winds.
6. Relief Features- High mountains act as barriers for winds and can cause precipitation; leeward sides tend to be dry.
Factors Affecting India’s Climate
Latitude
The Tropic of Cancer runs through India from Rann of Kuchchh (west) to Mizoram (east).
Half of India lies south of the Tropic, classified as tropical; the northern half is subtropical.
Altitude
Northern mountains average about 6,000 meters in height.
Coastal areas have a maximum elevation of about 30 meters.
The Himalayas block cold winds from Central Asia, resulting in milder winters compared to Central Asia.
Pressure and Winds
