Westerlies in southern hemisphere are stronger and persistent than in northern hemisphere. Why? 1. Southern hemisphere has less landmass as compared to northern hemisphere. 2. Coriolis force is higher in southern hemisphere as compared to northern hemisphere. Which of the statements given above is/are correct?
Contents17
- A1 only
- B2 only
- CBoth 1 and 2
- DNeither 1 nor 2
Show answer
Answer: (A) 1 only
Statement 1 is CORRECT:
The Southern Hemisphere has far less land (mostly ocean) compared to the Northern Hemisphere.
Land creates friction and obstacles that slow down winds.
Since the Southern Hemisphere between 40°-60°S is almost entirely ocean (called the 'Roaring Forties,' 'Furious Fifties,' and 'Screaming Sixties'), westerly winds blow uninterrupted and are therefore much stronger.
Statement 2 is WRONG:
The Coriolis force depends on LATITUDE (distance from equator), not on which hemisphere you're in.
At the same latitude, Coriolis force is equal in both hemispheres.
It just deflects winds to the right in the North and to the left in the South — but the STRENGTH is the same.
Key takeaway:
Less land → less friction → stronger winds.
Simple!
The Southern Hemisphere between 40°-60°S is almost entirely ocean with no major landmasses to create friction, while the Northern Hemisphere has large continents that disrupt wind flow.
Students often confuse Coriolis force strength with Coriolis effect direction - the force depends only on latitude and is equal at same latitudes in both hemispheres, just deflecting opposite ways.
Westerlies: Global Pattern & Characteristics
Geography Westerlies southern hemisphere northern hemisphere
Westerlies: Formation, Distribution & Hemispheric Differences
Westerlies blow from 30°-60° latitude in both hemispheres
Southern westerlies are stronger and more persistent than northern westerlies
Less landmass in southern hemisphere = less friction = stronger winds
Famous southern zones: Roaring Forties (40°-50°S), Furious Fifties (50°-60°S)
What Are Westerlies
Westerlies are planetary winds that blow from west to east between 30°-60° latitude in both hemispheres. They form due to pressure differences between the subtropical high-pressure belt (30°N/S) and subpolar low-pressure belt (60°N/S).
Northern vs Southern Westerlies
Aspect | Northern Hemisphere | Southern Hemisphere |
|---|---|---|
Land Coverage | Large continents (Asia, Europe, N. America) | Mostly ocean between 40°-60°S |
Wind Strength | Moderate, interrupted | Very strong, persistent |
Seasonal Variation | High variation due to land heating | Low variation, steady |
Friction | High friction from mountains, forests | Minimal friction over ocean |
Famous Names | Variable westerlies | Roaring Forties, Furious Fifties |
Question Connection
This PYQ tests why southern westerlies are stronger. Statement 1 correctly identifies less landmass as the reason. Statement 2 incorrectly claims Coriolis force differs between hemispheres — it's the same strength at equal latitudes.
Trap: Thinking Coriolis force is stronger in one hemisphere — it's equal at same latitudes, just direction differs
Trap: Confusing westerlies with trade winds — westerlies blow west to east, trades blow east to west
Trap: Forgetting that ocean = less friction while land = more friction for wind flow
Coriolis Force: Latitude Dependency
Geography Coriolis force
Coriolis Force: How Earth's Rotation Deflects Winds
Coriolis force depends on latitude, not hemisphere
Maximum at poles (90°), zero at equator (0°)
Deflects right in NH, left in SH — but strength is equal at same latitude
What Creates Coriolis Force
Coriolis force is the apparent deflection of moving objects (including air) due to Earth's rotation. It's not a real force but appears real to observers on rotating Earth. The deflection strength depends entirely on how fast the Earth rotates at your latitude.
Coriolis Force by Latitude
Latitude | Coriolis Force Strength | Wind Deflection | Example Locations |
|---|---|---|---|
0° (Equator) | Zero | No deflection | Amazon, Congo Basin |
30°N/S | Medium | Moderate deflection | Delhi, Cairo |
60°N/S | High | Strong deflection | Alaska, Antarctica |
90° (Poles) | Maximum | Maximum deflection | North/South Pole |
How Coriolis Works
%%{init: {"flowchart": {"wrappingWidth": 460}}}%%
flowchart TD
s1["`**Air moves from high to low pressure**
Wind wants to blow straight from high pressure to low pressure`"]
s2["`**Earth rotates beneath moving air**
Earth spins faster at equator, slower near poles`"]
s3["`**Air appears to curve**
To ground observers, wind seems to deflect right (NH) or left (SH)`"]
s4["`**Deflection creates wind patterns**
Creates cyclones, anticyclones, and global wind belts`"]
s1 --> s2
s2 --> s3
s3 --> s4Trap: Thinking Coriolis is stronger in one hemisphere — it's identical strength at equal latitudes
Trap: Confusing direction with strength — NH deflects right, SH deflects left, but force is same
Trap: Forgetting Coriolis is zero at equator — cyclones cannot form there
Land-Ocean Effects on Wind Speed
Geography landmass less landmass
How Surface Type Controls Wind Speed & Persistence
Ocean surfaces create minimal friction — winds blow faster
Land surfaces create high friction — winds slow down and become irregular
Mountains, forests, cities act as major wind barriers
Why Surface Matters
Wind speed depends heavily on surface friction. Smooth ocean surfaces allow winds to blow uninterrupted, while rough land surfaces create turbulence and slow winds down through friction and obstacles.
Surface Types & Wind Effects
Surface Type | Friction Level | Wind Speed | Wind Pattern | Example |
|---|---|---|---|---|
Open Ocean | Very Low | High, consistent | Steady, persistent | Southern Ocean westerlies |
Coastal Plains | Low-Medium | Moderate | Fairly steady | European plains |
Mountain Ranges | Very High | Low, turbulent | Irregular, gusty | Himalayas, Rockies |
Dense Forests | High | Low | Interrupted | Amazon, Siberian taiga |
Urban Areas | High | Low, channeled | Complex patterns | City wind corridors |
Southern Ocean Advantage
Between 40°-60°S, the Southern Hemisphere is almost entirely ocean with no major landmasses. This creates the Roaring Forties and Furious Fifties — the strongest and most persistent westerly winds on Earth.
Northern Hemisphere contrast: Large continents (Asia, Europe, North America) break up the westerly flow, creating seasonal variations and weaker average winds.
Trap: Thinking land helps wind flow — actually land slows wind through friction
Trap: Forgetting that ocean = smooth = fast winds while land = rough = slow winds
Trap: Not connecting Southern Ocean's continuous belt with stronger westerlies
Roaring Forties & Furious Fifties
Geography
Southern Ocean Wind Zones: The Stormiest Seas on Earth
Roaring Forties (40°-50°S) and Furious Fifties (50°-60°S) are notorious wind zones
Uninterrupted ocean allows westerlies to build tremendous speed
Historical sailing routes avoided these zones due to dangerous conditions
Also called Screaming Sixties beyond 60°S near Antarctica
The Windiest Waters
The Southern Ocean between 40°-60°S contains Earth's strongest surface winds. With no continental barriers, westerlies circle Antarctica uninterrupted, creating legendary wind zones that sailors have feared for centuries.
Southern Ocean Wind Zones
Zone Name | Latitude Range | Typical Wind Speed | Sea Conditions | Navigation Risk |
|---|---|---|---|---|
Roaring Forties | 40°-50°S | 40-50 km/h sustained | Large swells, rough | High |
Furious Fifties | 50°-60°S | 50-70 km/h sustained | Very rough, dangerous | Extreme |
Screaming Sixties | 60°-70°S | 60+ km/h sustained | Mountainous waves | Nearly impossible |
Southern Ocean Wind Map
Source: Global Solo Challenge — Roaring Forties and Furious Fifties? · globalsolochallenge.com
Why No Northern Equivalent
The Northern Hemisphere has no equivalent because large landmasses (Asia, Europe, North America) interrupt the westerly flow at similar latitudes. The North Atlantic and North Pacific are separated by continents, preventing the formation of continuous circumpolar winds.
Trap: Expecting similar wind zones in Northern Hemisphere — landmasses prevent this
Trap: Confusing the latitude ranges — Forties are 40°-50°S, Fifties are 50°-60°S
Trap: Thinking these are trade wind zones — they're westerly wind zones