Roaring Forties

Also called: Furious Fifties, Shrieking Sixties · Topic: Atmospheric Pressure, Winds and General Circulation · NCERT: Beyond NCERT

Meaning

The Roaring Forties are the strong, steady westerly winds (winds that blow from the west) of the Southern Hemisphere. They blow in the belt between 40° and 50°S, where they are often gale-force all year [2]. Further south, the same winds are called the Furious Fifties (50°–60°S) [3] and the Shrieking (Screaming) Sixties (around 60°S).

They matter because they are the clearest example of how land and sea shape wind. With almost no land in the way, the westerlies here are the strongest on Earth. They have shaped sailing routes, ocean currents and the weather of the far south.

Explanation

How they form: cause → process → result

• Cause: the pressure belts.
• Air moves from the subtropical high (a high-pressure belt near 30°S) towards the subpolar low (a low-pressure belt near 60°S).

• This poleward flow is the westerlies, the planetary wind of the middle latitudes.

• Process: the Coriolis force turns the wind.

• The Coriolis force is the turning effect of the Earth's spin on moving air. It turns air to the left in the Southern Hemisphere.

• So the poleward-moving air is turned to the east. It ends up blowing from the north-west.

• Result: the winds are strong and steady.

• The Southern Hemisphere is mostly ocean between 40° and 60°S.
• There are almost no mountains or land masses to slow the wind down by friction.
• So the westerlies blow fast and without a break, all year.

Why they are stormy

• The gales come with depressions (travelling low-pressure storms of the middle latitudes).
• The Roaring Forties are the latitude zone where these storm winds are most frequent [1].
• Near 60°S lies the polar front. This is the boundary where the cold polar easterlies meet the warmer, moist westerlies.
• The cold, heavy air pushes under the warm air.
• The warm air is forced up, and the front bends into waves.
• These waves grow into temperate cyclones, which keep feeding storms into the westerly belt.

The three belts: getting stronger towards the pole

Name	Latitude	Meaning of the name
Roaring Forties	40°–50°S [2]	Strong west winds that roar all year
Furious Fifties	50°–60°S [3]	Even fiercer winds
Shrieking (Screaming) Sixties	Around 60°S	The wildest belt, near the subpolar low

• Early sailors who first sailed into these latitudes gave them these names [2].
• Going towards the pole, the order is Roaring → Furious → Shrieking.

Where it occurs

• The world:
• In a ring around Antarctica, across the southern parts of the Atlantic, Indian and Pacific Oceans (the Southern Ocean).
• Southern Chile and New Zealand stand in the path of these westerlies. Their west coasts get rain all year and a steady stream of temperate cyclones.
• Europe–Australia sea route: in the 19th century, clipper ships (fast sailing ships) rode the Roaring Forties east to Australia.
• Round-the-world sailing races still use these winds today.

• Antarctic Circumpolar Current (West Wind Drift): these winds push this ocean current eastward around Antarctica.

• India:

• India lies in the Northern Hemisphere, so these winds do not blow over Indian land.
• The southern Indian Ocean, far south of India, lies in this belt. Indian expedition ships going to India's Antarctic research stations have to cross these stormy latitudes.

Don't confuse with

• Northern Hemisphere westerlies: these blow from the south-west, while the Roaring Forties blow from the north-west. They are also weaker, because large land masses in the north slow them down.
• Trade winds: these are the steadiest winds on Earth, but they blow from the east in the tropics (0°–30°). The Roaring Forties are the strongest winds and blow from the west in the mid-latitudes.
• Polar easterlies: these are cold, dry winds that blow from the east, from the polar high to the subpolar low (60°–90°). The Roaring Forties lie on the other side of the polar front, towards the equator.
• West Wind Drift: this is an ocean current, not a wind. The Roaring Forties and the other westerlies drive it.

Prelims Hooks

• Roaring Forties = 40°–50°S [2]; Furious Fifties = 50°–60°S [3]; Shrieking Sixties = around 60°S. Going towards the pole: Roaring → Furious → Shrieking.
• Trap: these belts are found only in the Southern Hemisphere. There is no "Roaring Forties" belt at 40°–50°N.
• Direction trap: Southern Hemisphere westerlies blow from the north-west, not the south-west. South-westerlies belong to the Northern Hemisphere.
• Why they are so strong: the Southern Hemisphere has almost no land between 40° and 60°S, so there is little friction to slow the wind.
• Wind–route match: Roaring Forties → clipper ships on the Europe–Australia route, and modern round-the-world sailing races.
• Gale-force all year [2]. The belt is the zone where depression-linked storm winds are most frequent [1].

Mains Points

• Land–sea distribution controls wind strength (GS-I): the westerlies blow in both hemispheres. In the north, continents break them up. In the south, the open ocean between 40° and 60°S lets them blow strong and steady. This is why gales are found all year in the Roaring Forties, Furious Fifties and Shrieking Sixties [2][3].
• Effects on oceans and climate (GS-I):
• The winds drive the Antarctic Circumpolar Current (West Wind Drift) around Antarctica.
• They bring year-round rain and temperate cyclones to the west coasts of southern Chile and New Zealand.

• Historically, they made the fast clipper-ship route to Australia possible.

• Resource potential and risks (GS-III): the steady, strong winds of this belt offer a large offshore wind-energy potential. But the frequent storms make shipping and polar expeditions risky, so ships need good weather warnings when they cross these latitudes.

Related concepts

• Trade winds
• Southeast trade winds
• Westerlies
• Polar easterlies
• Atmospheric river

Read more

• The planetary winds: trades, westerlies and polar easterlies