Planetary and Local Winds
Delhi Police & SSC Exams
1. Introduction: What Are Winds?
Definition:
- Winds: Horizontal movements of air
- Direction: From high pressure to low pressure
- Cause: Unequal heating of Earth's surface
- Classification: Planetary, Periodic, and Local winds
Wind Types:
Planetary (Permanent) Winds
Periodic Winds
Local Winds
Exam Trick: "Wind = Air in Motion. Direction = From High Pressure → Low Pressure"
2. Planetary Winds (Permanent Winds)
Trade Winds
- Direction: Subtropical High → Equatorial Low
- Northern Hemisphere: Northeast
- Southern Hemisphere: Southeast
- Effect: Bring moisture, cause rainfall near equator
Westerlies
- Location: 30°–60° latitude both hemispheres
- Northern Hemisphere: Southwest
- Southern Hemisphere: Northwest
- Effect: Influence temperate climates
Polar Easterlies
- Direction: Polar High → Subpolar Low
- Nature: Cold, dry winds
- Movement: East to West near poles
- Character: Strong and persistent
Exam Trick: "T-W-P = Trade → Westerlies → Polar (From Equator → Poles sequence)"
3. Local Winds
| Wind Name | Region | Nature | Description |
|---|---|---|---|
| Loo | Northern India | Hot & dry | Blows during summer |
| Mistral | France | Cold & dry | Blows down the Alps |
| Chinook | Rocky Mountains (USA/Canada) | Warm | "Snow eater" – melts snow quickly |
| Foehn | Alps (Europe) | Warm | Similar to Chinook |
| Sirocco | Sahara → Mediterranean | Hot & dusty | Carries desert dust |
| Bora | Adriatic Coast | Cold | Strong winter wind |
Exam Trick: "Hot Winds → Loo, Sirocco | Cold Winds → Bora, Mistral | Warm Snow-Melters → Chinook, Foehn"
4. Periodic Winds
Monsoon Winds
- Type: Seasonal reversal
- Summer: Sea to Land
- Winter: Land to Sea
- Regions: South Asia, Southeast Asia
Land Breeze
- Time: Night
- Direction: Land → Sea
- Cause: Land cools faster than sea
- Effect: Cooler coastal areas
Sea Breeze
- Time: Day
- Direction: Sea → Land
- Cause: Land heats faster than sea
- Effect: Moderates coastal temperature
Exam Trick: "Monsoon = Seasonal Swap of Winds | Sea Breeze = Daytime | Land Breeze = Nighttime"
PYQs (Delhi Police Exam)
Trade winds blow from:
Options: A) Poles to Equator B) Equator to Poles C) Subtropical High to Equatorial Low D) Subpolar Low to Equator
Category: Planetary Winds
Show Answer
C) Subtropical High to Equatorial Low
Which of the following winds is called the "Snow Eater"?
Options: A) Bora B) Chinook C) Loo D) Sirocco
Category: Local Winds
Show Answer
B) Chinook
The Westerlies blow between:
Options: A) 0°–30° B) 30°–60° C) 60°–90° D) 45°–90°
Category: Wind Locations
Show Answer
B) 30°–60°
Which of these is a cold local wind?
Options: A) Loo B) Foehn C) Bora D) Sirocco
Category: Wind Characteristics
Show Answer
C) Bora
5. Quick Revision Notes
Wind Types:
- Planetary Winds: Trade, Westerlies, Polar
- Local Winds: Loo (Hot, India), Mistral (Cold, France)
- Local Winds: Chinook (Warm, USA), Sirocco (Dusty, Sahara)
- Periodic Winds: Monsoon, Land & Sea Breeze
Key Principles:
- Direction: High Pressure → Low Pressure
- Coriolis Effect: Deflects winds (Right in North, Left in South)
- Temperature: Determines wind characteristics
- Seasonal: Monsoon winds reverse direction
6. Exam Tricks & Memory Aids
"TWP Rule" → Trade, Westerlies, Polar (Permanent winds order)
Hot → Loo, Sirocco | Cold → Bora, Mistral | Warm → Chinook, Foehn
Sea Breeze = Daytime | Land Breeze = Nighttime
Coriolis Effect = Wind Deflection due to Earth's rotation
Final Exam Tip
Delhi Police Geography questions often ask wind names, directions, and regions. Focus on Trade Winds + Local Winds table and difference between types for quick scoring. Remember the classification: Planetary, Periodic, and Local winds with their specific characteristics.
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