The movement of air in the Earth’s atmosphere is known as wind. Winds are generated mainly due to uneven heating of the Earth’s surface, which causes differences in air pressure. Air always moves from high-pressure areas to low-pressure areas, creating different types of wind systems across the globe.
NDA & CDS 1 2026 Exam Geography – Climatology – Class 2
1. Introduction
The movement of air in the Earth’s atmosphere is known as wind. Winds are generated mainly due to uneven heating of the Earth’s surface, which causes differences in air pressure. Air always moves from high-pressure areas to low-pressure areas, creating different types of wind systems across the globe.
2. Types of Winds
Winds are broadly classified into three categories:
(A) Permanent or Planetary Winds
These winds blow constantly throughout the year in a particular direction due to the Earth’s pressure belts and planetary wind system.
They include:
- Trade Winds: Blow from the subtropical high-pressure belts (30° N/S) towards the equatorial low-pressure belt. They are easterly winds (from east to west).
- Westerlies: Blow from 30°–60° latitude in both hemispheres towards the poles. They are westerly winds (from west to east).
- Polar Easterlies: Cold winds blowing from polar high pressure towards subpolar low pressure areas.
(B) Periodic Winds
These winds change their direction periodically with the season or time of day.
Examples:
- Monsoon Winds: Seasonal reversal of winds due to differential heating of land and sea. In summer, they blow from sea to land (rainy season); in winter, from land to sea (dry season).
- Land and Sea Breezes: Daily reversal of wind direction near coastal areas.
- Mountain and Valley Breezes: During day, wind moves up the valley; at night, it flows down the slopes.
(C) Local Winds
Local winds develop due to local temperature and pressure differences.
Examples:
- Loo (India): Hot and dry wind in northern India during summer.
- Chinook: Warm, dry wind on the eastern slopes of the Rockies in North America.
- Foehn: Warm wind on the leeward side of the Alps.
- Mistral: Cold wind blowing through the Rhone valley in France.
3. Cyclones
A cyclone is a large-scale air mass that rotates around a strong center of low atmospheric pressure. Winds blow inward and upward around the low-pressure area.
(A) Tropical Cyclones
- Form over warm ocean waters (temperature above 26°C).
- Originate between 5° and 20° latitude in both hemispheres.
- Known by different names:
- Hurricane – Atlantic Ocean
- Typhoon – Western Pacific
- Cyclone – Indian Ocean
- Willy-Willy – Australia
- Characteristics:
- Eye of the cyclone (calm region at center)
- Strong winds (120–250 km/h)
- Heavy rainfall and storm surges
- Examples in India: Cyclone Tauktae (2021), Cyclone Amphan (2020), Cyclone Fani (2019)
(B) Temperate (Mid-Latitude) Cyclones
- Form between 35°–65° latitudes.
- Develop due to interaction of warm and cold air masses (fronts).
- Move from west to east and are more extensive than tropical cyclones.
- Common over North Atlantic and North Pacific regions.
4. Anticyclones
An anticyclone is the opposite of a cyclone. It is a high-pressure system where winds blow outward and downward in a clockwise direction in the Northern Hemisphere and anticlockwise in the Southern Hemisphere.
Anticyclones bring clear skies, dry, and stable weather.
5. Importance of Studying Winds and Cyclones
- Help in predicting weather and climate patterns.
- Crucial for aviation, shipping, and agriculture.
- Understanding cyclones aids in disaster preparedness and reducing loss of life and property.
Conclusion
Winds and cyclones are vital components of the Earth’s atmospheric circulation system. They balance heat across the globe and influence regional climates. A deep understanding of these phenomena helps in better weather forecasting and climate studies, contributing to human safety and sustainable development.
