📌 Topic 06 of 6 · Chapter 11 · World Physical Geography
World Winds, Pressure Belts & Revision
Trade winds, westerlies, polar winds, pressure belts — complete revision for UPSC & PSC exams.
🌬️ Pressure Belts & Winds
| Pressure Belt | Location | Winds Blowing From |
|---|---|---|
| Equatorial Low Pressure | 0°–5° N & S | Calm zone (Doldrums); no winds; rising air |
| Sub-tropical High Pressure | 25°–35° N & S | Horse Latitudes; calm; descending air |
| Sub-polar Low Pressure | 60°–65° N & S | Rising air; cyclones form here |
| Polar High Pressure | 90° N & S | Cold descending air; polar winds blow outward |
🌬️ Planetary Winds
| Wind | Direction | Latitude | Key Facts |
|---|---|---|---|
| Trade Winds | From sub-tropical high to equatorial low | 5°–25° N & S | NE trades (N hemisphere); SE trades (S hemisphere); steady and reliable |
| Westerlies | From sub-tropical high to sub-polar low | 35°–60° N & S | Blow from west; bring rain to western coasts; “Roaring Forties” (40°S) |
| Polar Winds | From polar high to sub-polar low | 60°–90° N & S | Cold, dry winds; blow from east |
- Coriolis Effect: Due to Earth’s rotation — winds deflect to the right in Northern Hemisphere, left in Southern Hemisphere
- Cyclones: Anticlockwise in Northern Hemisphere; clockwise in Southern Hemisphere
- Roaring Forties: Strong westerly winds at 40°S — used by sailing ships
- Furious Fifties & Screaming Sixties: Even stronger westerlies at 50°S and 60°S
✅ Chapter 11 — Complete Revision Checklist
✅ Asia = largest continent; Australia = smallest; Antarctica = 5th largest
✅ Pacific = largest ocean; Arctic = smallest; Mariana Trench = deepest (11,034m)
✅ Equator = 0°; Tropic of Cancer = 23.5°N; Tropic of Capricorn = 23.5°S
✅ IST = 82.5°E = GMT + 5:30 = passes through Mirzapur (UP)
✅ International Date Line = 180° = date changes when crossed
✅ Gulf Stream = warm current = keeps Western Europe warm
✅ El Niño = warming of Pacific = weakens Indian monsoon
✅ Mt. Everest = 8,849m = world’s highest = Nepal/China border
✅ Andes = longest mountain range in world = South America
✅ Kilimanjaro = highest in Africa = Tanzania
✅ Nile = longest river (6,650 km); Amazon = largest by volume
✅ Caspian Sea = largest lake; Lake Baikal = deepest lake
✅ Angel Falls (Venezuela) = world’s highest waterfall (979m)
✅ Sahara = largest hot desert; Antarctic = largest desert overall
✅ Coriolis effect = winds deflect right in N hemisphere, left in S hemisphere
✅ Pacific = largest ocean; Arctic = smallest; Mariana Trench = deepest (11,034m)
✅ Equator = 0°; Tropic of Cancer = 23.5°N; Tropic of Capricorn = 23.5°S
✅ IST = 82.5°E = GMT + 5:30 = passes through Mirzapur (UP)
✅ International Date Line = 180° = date changes when crossed
✅ Gulf Stream = warm current = keeps Western Europe warm
✅ El Niño = warming of Pacific = weakens Indian monsoon
✅ Mt. Everest = 8,849m = world’s highest = Nepal/China border
✅ Andes = longest mountain range in world = South America
✅ Kilimanjaro = highest in Africa = Tanzania
✅ Nile = longest river (6,650 km); Amazon = largest by volume
✅ Caspian Sea = largest lake; Lake Baikal = deepest lake
✅ Angel Falls (Venezuela) = world’s highest waterfall (979m)
✅ Sahara = largest hot desert; Antarctic = largest desert overall
✅ Coriolis effect = winds deflect right in N hemisphere, left in S hemisphere