Understanding Climate and Weather

  1. Climate vs. Weather:
    • Climate: Average weather conditions over a long period (30+ years).
    • Weather: Atmospheric state at a specific place and time.
    • Both include elements like temperature, pressure, wind, humidity, and precipitation.
    • Climate patterns influence daily and seasonal weather (e.g., woolens in December, rain in June).
  2. India’s Climate:
    • India has a monsoon type of climate, with seasonal reversal of wind directions.
    • The term “monsoon” comes from the Arabic word ‘mausim’, meaning season.

Regional and Seasonal Variations

  1. Temperature Variations:
    • Extreme: Rajasthan may reach 50°C in summer; Drass, Jammu & Kashmir, can drop to -45°C in winter.
    • Moderate: Coastal areas like Kerala and Andaman have less temperature variation between day and night.
  2. Rainfall Variations:
    • Meghalaya receives over 400 cm annually, while Ladakh and Rajasthan get less than 10 cm.
    • Tamil Nadu receives significant rainfall during October-November due to cyclones.

Factors Influencing India’s Climate

  1. Latitude:
    • Tropic of Cancer divides India into tropical (south) and subtropical (north) zones.
  2. Altitude:
    • Himalayas block cold Central Asian winds, resulting in milder winters.
  3. Pressure and Winds:
    • Seasonal changes in pressure and wind directions govern monsoons and rainfall.
    • India lies in the northeast trade wind belt.
  4. Relief Features:
    • Mountains act as barriers, causing precipitation on windward sides and dry conditions on leeward sides.

Monsoons: Key Features

  1. Mechanism:
    • In summer: Low pressure over northwest India attracts moisture-laden southwest winds, causing rainfall.
    • In winter: Dry northeast trade winds dominate, bringing little rain except to Tamil Nadu.
  2. “Break” in Monsoon:
    • Alternating dry and wet spells within the rainy season.
  3. Unifying Role:
    • Monsoon rains influence agriculture, festivals, and livelihoods across India.

Seasonal Weather

  1. Winter (Cold Weather Season):
    • November-February: Clear skies, low temperatures, and occasional western disturbances causing rain in northern plains.
  2. Summer (Hot Weather Season):
    • March-May: Intense heat, formation of low pressure over northern India.
  3. Advancing Monsoon:
    • June-September: Onset of rainfall from southwest monsoon winds.
  4. Retreating Monsoon:
    • October-November: Monsoon winds withdraw; cyclones impact eastern coasts.

Climatic Controls

  1. Latitude, altitude, distance from sea (continentality), pressure/wind systems, ocean currents, and relief are key factors.
  2. Continentality causes extremes in interior regions compared to moderated coastal climates.

Additional Insights for Competitive Exams

  1. Coriolis Effect:
    • Deflects winds to the right in the northern hemisphere (Ferrel’s Law).
  2. Rainfall Distribution:
    • Declines from east (high in Assam) to west (low in Rajasthan) due to weakening monsoons.
  3. Agricultural Impact:
    • Monsoons support Rabi and Kharif crop cycles.
  4. Cyclones:
    • Affect coastal areas during retreating monsoon, causing heavy rain and destruction.

Practice Questions

  1. Match climatic controls (latitude, altitude, etc.) to their effects on temperature and rainfall.
  2. Analyze the impact of monsoon variability on agriculture.
  3. Explain why western deserts experience extreme temperatures.

Fun Facts

  • Mawsynram in Meghalaya is the wettest place on Earth.
  • Rajasthan houses are built with thick walls and flat roofs to combat heat, while Assam’s stilted homes prevent flood damage.

THESE ALL ARE THE NOTES OF CHAPTER 4 GEOGRAPHY. AND AFTER SOME TIME YOU GET IMPORTANT QUESTIONS HERE. *#THANKS FOR VISITING, VISIT AGAIN#* 😊