๐ Topic 06 of 6 ยท Chapter 11 ยท World Physical Geography
World Winds, Pressure Belts & Revision
Trade winds, westerlies, polar winds, pressure belts โ complete revision for UPSC & PSC exams.
๐ฌ๏ธ Pressure Belts & Winds
| Pressure Belt | Location | Winds Blowing From |
|---|---|---|
| Equatorial Low Pressure | 0ยฐโ5ยฐ N & S | Calm zone (Doldrums); no winds; rising air |
| Sub-tropical High Pressure | 25ยฐโ35ยฐ N & S | Horse Latitudes; calm; descending air |
| Sub-polar Low Pressure | 60ยฐโ65ยฐ N & S | Rising air; cyclones form here |
| Polar High Pressure | 90ยฐ N & S | Cold descending air; polar winds blow outward |
๐ฌ๏ธ Planetary Winds
| Wind | Direction | Latitude | Key Facts |
|---|---|---|---|
| Trade Winds | From sub-tropical high to equatorial low | 5ยฐโ25ยฐ N & S | NE trades (N hemisphere); SE trades (S hemisphere); steady and reliable |
| Westerlies | From sub-tropical high to sub-polar low | 35ยฐโ60ยฐ N & S | Blow from west; bring rain to western coasts; “Roaring Forties” (40ยฐS) |
| Polar Winds | From polar high to sub-polar low | 60ยฐโ90ยฐ N & S | Cold, dry winds; blow from east |
- Coriolis Effect: Due to Earth’s rotation โ 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 40ยฐS โ used by sailing ships
- Furious Fifties & Screaming Sixties: Even stronger westerlies at 50ยฐS and 60ยฐS
โ Chapter 11 โ Complete Revision Checklist
โ
Asia = largest continent; Australia = smallest; Antarctica = 5th largest
โ Pacific = largest ocean; Arctic = smallest; Mariana Trench = deepest (11,034m)
โ Equator = 0ยฐ; Tropic of Cancer = 23.5ยฐN; Tropic of Capricorn = 23.5ยฐS
โ IST = 82.5ยฐE = GMT + 5:30 = passes through Mirzapur (UP)
โ International Date Line = 180ยฐ = date changes when crossed
โ Gulf Stream = warm current = keeps Western Europe warm
โ El Niรฑo = warming of Pacific = weakens Indian monsoon
โ Mt. Everest = 8,849m = world’s highest = Nepal/China border
โ Andes = longest mountain range in world = South America
โ Kilimanjaro = highest in Africa = Tanzania
โ Nile = longest river (6,650 km); Amazon = largest by volume
โ Caspian Sea = largest lake; Lake Baikal = deepest lake
โ Angel Falls (Venezuela) = world’s highest waterfall (979m)
โ Sahara = largest hot desert; Antarctic = largest desert overall
โ Coriolis effect = winds deflect right in N hemisphere, left in S hemisphere
โ Pacific = largest ocean; Arctic = smallest; Mariana Trench = deepest (11,034m)
โ Equator = 0ยฐ; Tropic of Cancer = 23.5ยฐN; Tropic of Capricorn = 23.5ยฐS
โ IST = 82.5ยฐE = GMT + 5:30 = passes through Mirzapur (UP)
โ International Date Line = 180ยฐ = date changes when crossed
โ Gulf Stream = warm current = keeps Western Europe warm
โ El Niรฑo = warming of Pacific = weakens Indian monsoon
โ Mt. Everest = 8,849m = world’s highest = Nepal/China border
โ Andes = longest mountain range in world = South America
โ Kilimanjaro = highest in Africa = Tanzania
โ Nile = longest river (6,650 km); Amazon = largest by volume
โ Caspian Sea = largest lake; Lake Baikal = deepest lake
โ Angel Falls (Venezuela) = world’s highest waterfall (979m)
โ Sahara = largest hot desert; Antarctic = largest desert overall
โ Coriolis effect = winds deflect right in N hemisphere, left in S hemisphere