Class 11 : Geography (In English) – Lesson 9. Atmospheric Circulation and Weather Systems
EXPLANATION & SUMMARY
📘 1. Detailed Explanation (~1700+ Words)
🌍 Introduction
🌏 The Earth’s atmosphere is a dynamic, ever-changing system that plays a crucial role in shaping weather, climate, and life on the planet. It is in constant motion, redistributing heat and moisture around the globe through a complex set of movements known as atmospheric circulation. This circulation is driven by the uneven heating of Earth’s surface by solar radiation, the rotation of the Earth, pressure differences, and other forces.
🌦️ The movement of air masses, winds, cyclones, anticyclones, and monsoon systems are all part of this atmospheric circulation. These processes not only regulate the Earth’s temperature but also control precipitation patterns, storm formation, and climatic zones. Understanding them is essential for predicting weather, managing agriculture, preparing for disasters, and studying climate change.
🌐 Atmospheric Pressure and Wind Basics
🌬️ The primary driver of atmospheric motion is air pressure, the weight of air exerted on a unit area of the Earth’s surface. Winds are the horizontal movements of air from areas of high pressure to low pressure in order to balance atmospheric differences.
📊 Factors Affecting Air Movement
🌡️ Pressure Gradient Force (PGF):
The force that causes air to move from high to low pressure.
Greater the difference, faster the wind.
🌎 Coriolis Force:
Due to Earth’s rotation, winds are deflected:
➡️ Right in the Northern Hemisphere
⬅️ Left in the Southern Hemisphere
Deflection increases with latitude.
🌬️ Frictional Force:
Near Earth’s surface, friction slows wind speed and reduces Coriolis effect.
🪐 Centrifugal Force:
Outward force due to rotation, influencing curved wind paths.
🌪️ Types of Winds
Winds are categorized based on their scale and regularity into permanent, periodic, and local winds.
🌍 1. Permanent or Planetary Winds
🌐 These are large-scale winds that blow consistently throughout the year in specific directions due to the global pressure belts and Earth’s rotation.
📍 Major types:
☀️ Trade Winds:
Blow from subtropical high-pressure belts to equatorial low-pressure belts.
NE trades (Northern Hemisphere), SE trades (Southern Hemisphere).
🌬️ Westerlies:
Blow from subtropical highs towards subpolar lows (~30°–60° latitudes).
Stronger in the Southern Hemisphere due to less land obstruction.
🌨️ Polar Easterlies:
Cold, dry winds from polar highs to subpolar lows.
Deflected by Coriolis force towards the west.
🌊 2. Periodic Winds
These winds change direction periodically with seasons or time of day.
🌦️ Monsoons: Seasonal reversal of wind direction caused by differential heating of land and sea.
☀️ Land and Sea Breezes: Daily reversals due to temperature differences between land and water.
🌄 Mountain and Valley Breezes: Air flows upslope during the day and downslope at night.
🌬️ 3. Local Winds
Local topography and temperature differences produce short-duration winds:
🌵 Loo: Hot, dry summer wind in northern India.
🌾 Chinook: Warm, dry wind on the leeward side of Rockies.
🏜️ Foehn: Similar to Chinook in the Alps.
❄️ Mistral: Cold wind blowing from mountains to lowlands in Europe.
🌏 Atmospheric Circulation — The Global System
The general circulation of the atmosphere refers to the large-scale movement of air that redistributes heat and moisture from equatorial to polar regions. This global circulation pattern is divided into three main cells in each hemisphere.
🌍 1. Hadley Cell (0°–30°)
🌞 Warm air rises at the equator (low pressure) and moves poleward at high altitudes.
🌊 It cools, descends at ~30° latitude, forming subtropical high-pressure zones.
🌬️ Surface winds blow back towards the equator, forming trade winds.
🌎 2. Ferrel Cell (30°–60°)
🌡️ Air moves poleward at the surface from subtropical highs towards subpolar lows.
🌪️ Deflected by Coriolis force, forming westerlies.
🌬️ Air rises at subpolar lows and moves equatorward aloft.
🌏 3. Polar Cell (60°–90°)
❄️ Cold, dense air sinks at the poles, creating polar highs.
🌬️ Winds blow outward as polar easterlies towards subpolar lows.
🌡️ Warm air rising at ~60° forms a convection loop with polar air.
🌀 Pressure and Wind Belts of the World
🌐 Global atmospheric circulation results in distinct pressure and wind belts:
🌞 Equatorial Low Pressure Belt (ITCZ): Rising warm air, heavy rainfall.
🌤️ Subtropical High Pressure Belt: Descending air, dry and stable.
🌦️ Subpolar Low Pressure Belt: Convergence of warm westerlies and cold polar easterlies.
❄️ Polar High Pressure Belt: Cold, dense sinking air.
These belts shift seasonally with the apparent movement of the Sun, influencing global climate zones.
🌪️ Jet Streams
🌬️ Jet streams are narrow bands of fast-moving air found in the upper troposphere (9–14 km). They form at boundaries of contrasting temperature air masses.
📊 Characteristics:
Speed: 120–400 km/h
Width: 100–300 km
Major Types: Subtropical Jet, Polar Front Jet
📍 Importance:
Influence weather systems and storm tracks.
Affect aviation by reducing or increasing flight time.
Play a role in monsoon dynamics in South Asia.
🌦️ Air Masses and Fronts
🌎 Air masses are large bodies of air with uniform temperature and humidity characteristics. They develop over source regions like oceans and continents.
📊 Types of Air Masses:
🌊 Maritime Tropical (mT) – Warm, moist
🌍 Continental Tropical (cT) – Hot, dry
❄️ Continental Polar (cP) – Cold, dry
🌫️ Maritime Polar (mP) – Cool, moist
🧊 Arctic (A) – Very cold, dry
When air masses of different characteristics meet, they form fronts — boundaries with intense weather activity.
📍 Types of Fronts:
☁️ Cold Front: Cold air displaces warm air → thunderstorms, heavy rain.
🌧️ Warm Front: Warm air overrides cold air → gentle rain, cloudiness.
🌨️ Stationary Front: Air masses meet but do not move → prolonged weather.
🌪️ Occluded Front: Cold front overtakes warm front → complex weather.
🌀 Weather Systems: Cyclones and Anticyclones
Atmospheric circulation gives rise to rotating weather systems — cyclones (low pressure) and anticyclones (high pressure).
🌪️ 1. Cyclones
Cyclones are large-scale air systems with inward-spiraling winds around a low-pressure center.
📍 Characteristics:
Converging winds rise, cool, and condense → clouds and rainfall.
Associated with unstable weather and storms.
📊 Types:
🌊 Tropical Cyclones:
Form over warm oceans (above 27°C).
Strongest weather systems (e.g., hurricanes, typhoons).
Example: Cyclone Fani (2019, Bay of Bengal).
🌪️ Extratropical Cyclones:
Form in mid-latitudes along polar fronts.
Less intense but widespread precipitation.
🌤️ 2. Anticyclones
Anticyclones are high-pressure systems with outward-spiraling winds.
📍 Characteristics:
Descending air → clear skies and dry weather.
Stable conditions, often associated with heat waves or cold spells.
📊 Comparison:
Feature
Cyclone 🌪️
Anticyclone 🌤️
Pressure
Low
High
Wind Direction
Inward, counterclockwise (NH)
Outward, clockwise (NH)
Weather
Cloudy, rainy, stormy
Clear, dry, stable
🌍 Seasonal Shifts in Atmospheric Circulation
The position of pressure belts and wind systems changes with the apparent migration of the Sun between the Tropics of Cancer and Capricorn. This affects weather patterns globally.
📊 Examples:
🌞 ITCZ Shifts: Moves northward in summer → monsoons in South Asia.
❄️ Subtropical Jet Stream: Moves southward in winter → affects temperate cyclones.
🌬️ Trade Winds: Strength and position change seasonally.
🌦️ Monsoons: A Special Weather System
🌧️ Monsoons are seasonal winds reversing direction due to differential heating of land and sea. They are a crucial weather system for tropical and subtropical regions, especially in South Asia.
📍 Mechanism:
In summer, land heats faster → low pressure → moist oceanic winds bring rain.
In winter, land cools faster → high pressure → dry winds blow seaward.
📊 Features of Indian Monsoon:
Onset: June (Southwest Monsoon)
Retreat: October (Northeast Monsoon)
Seasonal reversal, heavy rainfall, crucial for agriculture.
🌡️ Weather vs. Climate
📊 Weather: Short-term atmospheric conditions (temperature, pressure, humidity, wind, precipitation) at a particular time and place.
📊 Climate: Long-term average of weather conditions over a region (usually 30+ years).
📍 Relationship: Weather represents daily variations, while climate represents broader patterns influenced by atmospheric circulation.
🌎 Role of Atmospheric Circulation in Climate and Life
🌡️ Heat Redistribution: Transfers energy from equator to poles, balancing Earth’s temperature.
☁️ Moisture Transport: Drives the global water cycle and precipitation.
🌦️ Weather Patterns: Determines storms, rainfall, and dry periods.
🌱 Ecosystem Regulation: Influences vegetation zones and agriculture.
🌍 Human Activities: Impacts settlement, transport, trade, and disaster preparedness.
📚 2. Summary (~300 Words)
Atmospheric circulation refers to the large-scale movement of air in the atmosphere, redistributing heat and moisture from the equator to the poles. It is driven by differences in pressure, temperature, Earth’s rotation, and solar radiation. Winds flow from high to low pressure, influenced by the Coriolis force and friction. Global circulation consists of three cells — Hadley, Ferrel, and Polar — forming distinct wind belts like trade winds, westerlies, and polar easterlies.
Jet streams, air masses, and fronts significantly affect weather systems. Cyclones (low-pressure systems) bring clouds and rainfall, while anticyclones (high-pressure systems) result in clear and stable weather. The meeting of air masses creates fronts, leading to diverse weather phenomena.
Seasonal shifts in circulation patterns, such as the migration of the ITCZ and changes in jet streams, drive monsoon systems. Monsoons, characterized by seasonal wind reversals, are crucial for rainfall in tropical regions like South Asia.
Atmospheric circulation regulates global climate, controls weather, and shapes ecosystems. Understanding its dynamics is essential for forecasting weather, mitigating natural disasters, planning agriculture, and managing water resources. It connects local weather patterns with global climate systems and influences the distribution of life and human activities across the planet.
⚡ 3. Quick Recap (~100 Words)
Atmospheric circulation is the global movement of air that redistributes heat and moisture, driven by pressure differences, Earth’s rotation, and solar energy. Planetary winds, jet streams, air masses, and fronts shape weather systems. Cyclones bring storms and rain, while anticyclones create clear weather. Seasonal shifts in circulation cause phenomena like monsoons. This circulation controls temperature distribution, precipitation, and climate zones, influencing ecosystems, agriculture, and human life. Understanding these processes is vital for predicting weather, managing disasters, and addressing climate change.
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QUESTIONS FROM TEXTBOOK
📘 Questions and Answers (Questions and Answers Together)
✨ 1. Multiple Choice Questions (MCQs)
🔴 Q1: If the surface air pressure is 1,000 mb, the air pressure at 1 km above the surface will be:
🟢 (a) 700 mb
🔵 (b) 1,100 mb
🟡 (c) 900 mb
🟣 (d) 1,300 mb
✅ Answer: 🟡 (c) 900 mb
🟠 Q2: The Inter Tropical Convergence Zone normally occurs:
🟢 (a) near the Equator
🔵 (b) near the Tropic of Cancer
🟡 (c) near the Tropic of Capricorn
🟣 (d) near the Arctic Circle
✅ Answer: 🟢 (a) near the Equator
🟡 Q3: The direction of wind around a low pressure in the northern hemisphere is:
🟢 (a) clockwise
🔵 (b) perpendicular to isobars
🟡 (c) anti-clockwise
🟣 (d) parallel to isobars
✅ Answer: 🟡 (c) anti-clockwise
🟣 Q4: Which one of the following is the source region for the formation of air masses?
🟢 (a) the Equatorial forest
🔵 (b) the Himalayas
🟡 (c) the Siberian Plain
🟣 (d) the Deccan Plateau
✅ Answer: 🟡 (c) the Siberian Plain
✏️ 2. Short Answer Questions (About 30 Words Each)
🔴 Q1: What is the unit used in measuring pressure? Why is the pressure measured at station level reduced to the sea level in preparation of weather maps?
🌱 Answer: Air pressure is measured in millibars (mb) or hectopascals (hPa). Since pressure decreases with altitude, it is reduced to sea level to compare data from different elevations accurately on weather maps.
🟠 Q2: While the pressure gradient force is from north to south, i.e., from the subtropical high pressure to the equator in the northern hemisphere, why are the winds north easterlies in the tropics?
🌱 Answer: Due to the Coriolis force caused by Earth’s rotation, winds moving from high to low pressure in the northern hemisphere are deflected to the right, becoming north-easterly trade winds.
🟣 Q3: What are the geostrophic winds?
🌱 Answer: Geostrophic winds are winds that flow parallel to isobars due to the balance between the pressure gradient force and the Coriolis force. They are common in the upper atmosphere where friction is negligible.
🔵 Q4: Explain the land and sea breezes.
🌱 Answer: Land and sea breezes are local winds caused by differential heating of land and water. During the day, cool air from the sea flows toward land (sea breeze). At night, cool air from the land moves toward the sea (land breeze).
📜 3. Long Answer Questions (About 150 Words Each)
🔴 Q1: Discuss the factors affecting the speed and direction of wind.
🌱 Answer:
Pressure Gradient Force (PGF): Winds blow from high to low pressure; stronger gradients cause faster winds.
Coriolis Force: Due to Earth’s rotation, winds deflect right in the northern hemisphere and left in the southern.
Frictional Force: Reduces wind speed near the surface and alters direction.
Centrifugal Force: Affects wind direction in curved motion.
Temperature and Density: Warm air rises, creating low pressure and affecting wind circulation.
These factors interact to produce global wind patterns such as trade winds, westerlies, and polar easterlies, and influence local systems like monsoons and cyclones.
🟢 Q2: Draw a simplified diagram to show the general circulation of the atmosphere over the globe. What are the possible reasons for the formation of subtropical high pressure over 30° N and S latitudes?
🌱 Answer: Subtropical highs form due to descending air from the Hadley cells. Warm air rises at the equator, moves poleward in the upper troposphere, cools, and descends at about 30° N and S. The Coriolis force spreads this air, creating high-pressure zones. Other factors include thermal contraction and convergence of winds aloft. These high-pressure belts are associated with deserts and dry climates and play a major role in global wind circulation.
🟣 Q3: Why does tropical cyclone originate over the seas? In which part of the tropical cyclone do torrential rains and high velocity winds blow and why?
🌱 Answer: Tropical cyclones form over warm ocean waters (>27°C) that provide moisture and latent heat, fueling convection. The Coriolis force initiates rotation. Torrential rains and strong winds occur around the eye wall, where intense convection, rapid air uplift, and condensation release huge amounts of energy. The rising moist air spirals upward, creating low pressure at the center and drawing in more air, sustaining the cyclone’s power.
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OTHER IMPORTANT QUESTIONS FOR EXAMS
🌏 Section A — Multiple Choice Questions (1 mark each)
🔵 Question 1: The movement of air in the atmosphere is primarily caused by:
🟢 1️⃣ Unequal heating of Earth’s surface
🔴 2️⃣ Ocean salinity differences
🟡 3️⃣ Earth’s shape
🔴 4️⃣ Magnetic field
✔️ Answer: Unequal heating of Earth’s surface
🟡 Question 2: Which force deflects the direction of winds on Earth’s surface?
🟢 1️⃣ Coriolis force
🔴 2️⃣ Frictional force
🟡 3️⃣ Gravitational force
🔴 4️⃣ Centripetal force
✔️ Answer: Coriolis force
🔴 Question 3: Winds that blow constantly in the same direction all year round are called:
🟢 1️⃣ Permanent winds
🔴 2️⃣ Local winds
🟡 3️⃣ Seasonal winds
🔴 4️⃣ Monsoons
✔️ Answer: Permanent winds
🟢 Question 4: Trade winds in the Northern Hemisphere blow from:
🟢 1️⃣ Northeast to southwest
🔴 2️⃣ Northwest to southeast
🟡 3️⃣ Southeast to northwest
🔴 4️⃣ Southwest to northeast
✔️ Answer: Northeast to southwest
🔵 Question 5: The low-pressure belt near the equator is known as:
🟢 1️⃣ Doldrums
🔴 2️⃣ Horse latitudes
🟡 3️⃣ Polar front
🔴 4️⃣ Subtropical high
✔️ Answer: Doldrums
🟡 Question 6: Which of the following winds is known as the “westerlies”?
🟢 1️⃣ Winds blowing from subtropical high to subpolar low
🔴 2️⃣ Winds blowing from polar high to subpolar low
🟡 3️⃣ Winds blowing from equator to poles
🔴 4️⃣ Winds blowing from east to west
✔️ Answer: Winds blowing from subtropical high to subpolar low
🔴 Question 7: Which pressure belt is associated with heavy rainfall and rising air?
🟢 1️⃣ Equatorial low
🔴 2️⃣ Subtropical high
🟡 3️⃣ Polar high
🔴 4️⃣ Subpolar low
✔️ Answer: Equatorial low
🟢 Question 8: The subtropical high-pressure belt is formed due to:
🟢 1️⃣ Descending air from the Hadley cell
🔴 2️⃣ Rising air from the equator
🟡 3️⃣ Coriolis force deflection
🔴 4️⃣ Polar winds convergence
✔️ Answer: Descending air from the Hadley cell
🔵 Question 9: Which type of wind is a warm, dry wind descending on the leeward side of mountains?
🟢 1️⃣ Chinook
🔴 2️⃣ Monsoon
🟡 3️⃣ Sirocco
🔴 4️⃣ Bora
✔️ Answer: Chinook
🟡 Question 10: Jet streams are:
🟢 1️⃣ Narrow bands of strong winds in the upper troposphere
🔴 2️⃣ Surface trade winds
🟡 3️⃣ Local winds
🔴 4️⃣ Monsoon winds
✔️ Answer: Narrow bands of strong winds in the upper troposphere
🔴 Question 11: The monsoon is caused mainly by:
🟢 1️⃣ Differential heating and cooling of land and water
🔴 2️⃣ Earth’s rotation
🟡 3️⃣ Ocean currents
🔴 4️⃣ Polar winds
✔️ Answer: Differential heating and cooling of land and water
🟢 Question 12: Cyclones in the Northern Hemisphere rotate:
🟢 1️⃣ Counter-clockwise
🔴 2️⃣ Clockwise
🟡 3️⃣ Vertically
🔴 4️⃣ Randomly
✔️ Answer: Counter-clockwise
🧭 Section B — Short Answer Questions (15–20 words each)
🔵 Question 13: Define atmospheric circulation.
🟢 Answer: Atmospheric circulation is the large-scale movement of air distributing heat and moisture around Earth’s surface.
🟡 Question 14: What is Coriolis force?
🟢 Answer: Coriolis force is the deflection of moving air due to Earth’s rotation, causing winds to curve.
🔴 Question 15: What are trade winds?
🟢 Answer: Trade winds are permanent easterly winds blowing from subtropical highs to the equatorial low-pressure belt.
🟢 Question 16: What is the Inter-Tropical Convergence Zone (ITCZ)?
🟢 Answer: The ITCZ is a zone near the equator where trade winds from both hemispheres converge, causing rising air and rainfall.
🔵 Question 17: What are jet streams?
🟢 Answer: Jet streams are fast-moving, narrow bands of high-altitude winds located near the tropopause.
🟡 Question 18: Define monsoon.
🟢 Answer: Monsoon is a seasonal reversal of wind direction caused by differential heating and cooling of land and water.
🔴 Question 19: What is a cyclone?
🟢 Answer: A cyclone is an intense low-pressure system with inward-spiraling winds rotating counter-clockwise in the Northern Hemisphere.
🟢 Question 20: What is a local wind? Give one example.
🟢 Answer: Local winds are small-scale winds influenced by local conditions. Example: Chinook, a warm dry wind in North America.
🌍 Section C — Medium Answer Questions (≈60 words each)
🔵 Question 21: Explain the three-cell model of atmospheric circulation.
🟢 Answer: The three-cell model divides each hemisphere into three circulation cells:
Hadley cell: Warm air rises at the equator and descends at 30° latitude, forming trade winds.
Ferrel cell: Air moves poleward from subtropical highs and returns at subpolar lows.
Polar cell: Cold air descends at poles and flows toward 60° latitude.
These cells distribute heat globally.
🟡 Question 22: Describe the pressure belts of the Earth.
🟢 Answer: Earth has alternating high and low-pressure belts:
Equatorial Low (0°): Rising warm air and heavy rainfall.
Subtropical High (30°): Descending dry air, deserts.
Subpolar Low (60°): Convergence of westerlies and polar winds.
Polar High (90°): Cold descending air.
These belts shift seasonally, influencing global wind patterns and weather systems.
🔴 Question 23: What are jet streams? Explain their significance.
🟢 Answer: Jet streams are high-speed winds (150–300 km/h) flowing near the tropopause at 8–15 km altitude. They form at boundaries of major air masses due to temperature contrasts. Jet streams influence weather patterns, steering cyclones and anticyclones, and impact aviation by affecting flight routes and times. They also play a key role in monsoon onset.
🟢 Question 24: Explain the mechanism of monsoon formation.
🟢 Answer: Monsoons form due to differential heating of land and water. In summer, the Asian landmass heats faster, creating a low-pressure area, drawing in moist winds from the Indian Ocean. These winds rise, cool, and cause rainfall. In winter, high pressure over land reverses wind direction. The seasonal shift of the ITCZ also supports monsoon circulation.
🔵 Question 25: What are cyclones? Describe their main features.
🟢 Answer: Cyclones are intense low-pressure systems with inward-spiraling winds. They feature:
A low-pressure center (eye) with calm weather.
Spiral winds rotating counter-clockwise in the Northern Hemisphere.
Heavy rainfall and strong winds.
Formation over warm oceans (>26°C).
Cyclones transfer heat from tropics to poles and significantly influence global weather and rainfall distribution.
🟡 Question 26: Explain the differences between tropical and temperate cyclones.
🟢 Answer: Tropical cyclones form over warm oceans, are intense, small (200–500 km), and powered by latent heat. They move westward and cause heavy rainfall. Temperate cyclones form in mid-latitudes, are larger (1000 km+), driven by temperature contrasts between air masses, and move eastward. Tropical cyclones form in summer, while temperate ones occur year-round.
🏞️ Section D — Detailed Answer Questions (≈150 words each)
🔴 Question 27: Describe the planetary pressure belts and their significance.
🟢 Answer: Planetary pressure belts are alternating zones of high and low pressure due to differential heating and Earth’s rotation.
Equatorial Low (0°): Rising warm air forms a low-pressure belt, causing convectional rainfall.
Subtropical High (30°): Descending dry air forms high pressure, leading to deserts.
Subpolar Low (60°): Rising air at polar front brings storms and cyclones.
Polar High (90°): Cold descending air forms stable high pressure.
These belts shift with the seasons, influencing global wind systems like trade winds, westerlies, and polar easterlies. They control climatic zones, precipitation patterns, and vegetation distribution. Understanding pressure belts is essential for predicting weather systems, monsoons, and climatic variability across latitudes.
🟢 Question 28: Discuss the causes and impacts of monsoons in detail.
🟢 Answer: Monsoons are seasonal wind reversals caused by differential heating of land and sea, shifting of the ITCZ, Coriolis force, and jet streams. In summer, low pressure over Asia draws moist winds from the oceans, bringing heavy rainfall. In winter, high pressure over land causes dry offshore winds. Impacts:
Provide essential rainfall for agriculture in Asia and Africa.
Support ecosystems and recharge water resources.
Cause floods and landslides in heavy rainfall areas.
Influence trade, economy, and lifestyle.
Irregular monsoons lead to droughts and food insecurity.
Monsoons are vital for global climate balance, as they redistribute heat and moisture and sustain biodiversity and human societies in tropical and subtropical regions.
🔵 Question 29: Explain the formation, structure, and effects of tropical cyclones.
🟢 Answer: Formation: Tropical cyclones develop over warm ocean waters (>26°C) with high humidity, Coriolis force, and unstable air. Rising warm air creates a low-pressure center, drawing in moist air, which releases latent heat, fueling the system.
Structure:
Eye: Calm, low-pressure center.
Eye wall: Strongest winds and heaviest rain.
Rain bands: Spiraling clouds extending outward.
Effects: Cyclones bring heavy rainfall, floods, and storm surges, damaging life and property. They disrupt communication and transport but also redistribute heat and maintain Earth’s energy balance. Preparedness and early warning systems reduce impacts, making cyclone study crucial for disaster management and climate science.
🟡 Question 30: Discuss the global wind system and its climatic significance.
🟢 Answer: The global wind system comprises three major belts:
Trade winds (0°–30°): Blow from subtropical highs to equatorial low, bringing moisture and rainfall.
Westerlies (30°–60°): Carry warm air to higher latitudes and influence mid-latitude cyclones.
Polar easterlies (60°–90°): Bring cold, dry air from polar highs.
These winds are driven by pressure gradients, Coriolis force, and differential heating. They transport heat, moisture, and energy, regulating Earth’s climate and weather systems. Wind patterns determine precipitation zones, desert formation, and ocean currents. Seasonal shifts influence monsoons and tropical weather. Understanding wind systems helps in forecasting climate change, navigation, and global circulation models essential for agriculture, transport, and disaster preparedness.
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ONE PAGE REVISION SHEET
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MIND MAPS
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