Named regional winds of the world

Detail

1. What a "local wind" is

• Local (regional) wind: a wind that blows over a small area for a short season. It comes from local differences in pressure, relief or surface heating. It is not part of the planetary belts (trade winds, westerlies, polar easterlies).
• Local winds take their nature from the place they start and the ground they cross:
• Source region: desert air is hot and dry. Polar or snow-covered land gives cold air.
• Relief: mountains force air up or down. Valleys channel it.

• Pressure gradient: a steep difference between high and low pressure makes the wind strong.

• They fall into three groups: warm, dry descending winds, hot, dry desert winds and cold winds.

2. Warm, dry descending winds (foehn type)

The mechanism (cause → process → result)

• Adiabatic change: the air heats or cools only because it is squeezed or allowed to expand. No heat is added or taken away.
• Dry adiabatic lapse rate (DALR): unsaturated air cools by about 10 °C per km as it rises and warms by the same amount as it sinks.
• Saturated (wet) adiabatic lapse rate: saturated air cools more slowly, by about 5–6 °C per km. As water vapour condenses it gives out latent heat (heat stored in water vapour and released when it becomes liquid).
• Step-by-step:
• Windward side (the side facing the wind):
  • Moist air is forced up the mountain.
  • It cools and becomes saturated.
  • Rain or snow falls. Above the cloud base the air cools only at the slow wet rate.
• Summit: the air has lost most of its moisture.
• Leeward side (the side away from the wind):
  • The dry air sinks and is squeezed.
  • It warms at the fast dry rate of about 10 °C/km.

• Result: the air reaches the foot of the leeward slope warmer and much drier than it was at the same height on the windward side. It melts snow quickly. Class 11 NCERT describes this process but does not name the wind.

• The leeward side therefore lies in a rain shadow (a dry area behind a mountain). Examples are the Deccan east of the Western Ghats and Patagonia east of the Andes.

Named winds of this type

Wind	Region	Season	Main effects
Foehn (föhn)	North-facing valleys of the Alps (Switzerland, Austria), about 46–47° N	Mainly spring and autumn	Melts snow early; helps grapes ripen; raises avalanche and fire risk
Chinook	Eastern slopes of the Rockies (Alberta in Canada; Montana and Wyoming in the USA)	Winter and spring	The "snow eater": clears snow from pastures so cattle can graze; can raise temperature by 20 °C or more within hours
Zonda	Eastern (leeward) slopes of the Andes, Argentina (Mendoza–San Juan)	Mainly May–November	Hot, dry and dusty; harms crops and health
Norwester	Canterbury Plains, east of the Southern Alps, South Island, New Zealand	Spring and summer	Hot, dry, gusty; dries the soil

• Foehn: a warm, dry wind that blows down the lee side of a mountain range. "Foehn" is also the general name scientists use for every wind of this type.
• Chinook: the foehn of North America. The name means "snow eater". In winter it shortens the time cattle must be fed indoors.

3. Hot, dry winds from deserts

3a. Saharan winds blowing north to the Mediterranean

• Sirocco: a hot, dusty south or south-east wind from the Sahara. It blows across North Africa to southern Europe (Sicily, southern Italy).
• Cause: depressions moving east across the Mediterranean draw desert air north ahead of them.
• Process: the air is dry when it leaves Africa. It picks up moisture over the Mediterranean.

• Result: it reaches Italy hot and humid (muggy). Red Saharan dust falling with rain makes "blood rain".

• Related Saharan winds:

Wind	Country	Notes
Khamsin	Egypt	Hot, dry, dusty; spring; the name comes from Arabic "fifty" (about 50 days)
Ghibli	Libya	Hot, dry, dust-laden
Leveche	South-east Spain	Hot, dry; brings dust from North Africa

3b. Harmattan (West Africa)

• Harmattan: a dry, dusty north-easterly from the Sahara over West Africa (Nigeria, Ghana, Côte d'Ivoire, Senegal), from about November to March.
• Why it blows: in the northern winter the ITCZ (Inter Tropical Convergence Zone: the low-pressure belt near the equator where the trade winds of the two hemispheres meet) shifts south. The north-east trades then blow straight out of the Sahara.
• Effects:
• Very low humidity and thick dust haze. Visibility drops and flights are disrupted.
• Called "the doctor" because its dry air relieves the hot, humid weather of the Guinea coast. Sweat evaporates, so people feel cooler.
• It also cracks the skin and dries out crops.

3c. Santa Ana winds (California, USA)

• Santa Ana winds: hot, dry offshore winds (blowing from the land out to sea). They come from the inland deserts and the Great Basin and blow to coastal southern California in autumn and winter.
• Cause → process → result:
• Cause: high pressure builds over the Great Basin and pressure is lower over the Pacific. The steep gradient drives air towards the coast between October and January [3].
• Process: the air rushes down the mountain ranges towards the coast. As it sinks it is squeezed, so it warms and becomes drier, like a foehn [3].

• Result: strong gusts, very low humidity and dry vegetation, which spreads wildfires fast.

• Case study: Los Angeles fires, January 2025

• The Palisades Fire started on the morning of 7 January 2025 near Pacific Palisades. It burned more than 11,000 acres (44 sq km) by the afternoon of 8 January [3].
• The Eaton Fire started on the evening of 7 January 2025 in Altadena. It spread over more than 10,000 acres and affected Pasadena and Altadena [3].
• Santa Ana gusts reached up to 100 miles per hour (about 160 km/h) [3].
• Gusts were forecast above the 98th percentile over both fire sites. Some gusts in the nearby mountains were forecast to exceed the historic maximum [2].
• The two fires rank second and third on California's list of most destructive fires [2].
• Background conditions:
  • Two wet winters (2022-23, among the 10 wettest on record, and 2023-24) grew dense vegetation [2].
  • October–December 2024 brought the driest start to the wet season on record, which dried that vegetation into fuel [2].
  • Los Angeles airport recorded only 0.03 inches of rain, its driest water-year start since records began in 1944 [3].
• La Niña link: the developing La Niña (cool phase of the Pacific in which the eastern tropical Pacific is colder than normal) likely added to the extreme fire weather. NOAA puts its effect at about the same size as that of global warming [2].
• Satellites: ESA's Sentinel-2 and NASA's Aqua (MODIS) imaged the smoke streaming over the Pacific [3].

3d. Loo (India) and brickfielder (Australia)

• Loo: a hot, dry westerly that blows in the afternoon over the north-western plains of India (Punjab, Haryana, Delhi, Rajasthan, Uttar Pradesh, Bihar) in May–June.
• Cause: intense summer heating creates low pressure over north-west India.
• Process: hot air from the Thar Desert and lands further west moves east. Bringing heat in from another place like this is advection (heat carried sideways by moving air).
• Result: temperatures of 45–50 °C, heatstroke (sunstroke) and heatwave deaths.

• It ends when the monsoon arrives in late June–July.

• Brickfielder: a hot, dry, dusty wind from Australia's interior desert that blows over south-east Australia (Victoria, New South Wales) in summer. It is the Australian equivalent of the loo.

4. Cold winds

Wind	Region	Nature	Season
Mistral	Rhône valley to the Mediterranean coast of France (Gulf of Lion)	Cold, dry, strong northerly	Winter and spring
Bora	Adriatic coast (Trieste, Croatia), off the Dinaric Alps	Cold, dry, gusty north-easterly	Winter
Blizzard	North America (Canadian and US plains)	Snow-laden polar wind, very strong	Winter
Purga / Buran	Siberia (purga) and Central Asia, Kazakh steppes (buran)	Snow-laden polar wind, very strong	Winter
Pampero	Pampas of Argentina (and Uruguay)	Cold, strong south-westerly from the Antarctic side; often brings squalls	Mainly winter and spring

• Mistral: a cold, dry, strong northerly wind. It is funnelled down the Rhône valley from the Alps and central France to the Mediterranean coast.
• Cause: high pressure over central France and a depression over the Gulf of Lion.
• Process: cold air drains towards the low. The narrow Rhône valley squeezes it, so it speeds up (the funnel effect).

• Result: freezing gusts damage crops. Farmers plant rows of cypress trees as windbreaks to protect vineyards and orchards. Houses in Provence face south and have few north-facing windows.

• Blizzard: a violent, very cold wind full of fine snow. Visibility falls almost to zero.

5. Map exercise

Mark each wind on a world outline map with its region. Use red for hot/warm winds and blue for cold winds, and mark each "D" (dry) or "M" (moist).

• Hot or warm, dry: foehn (Alps), chinook (Rockies), zonda (Argentina), norwester (New Zealand), harmattan (West Africa), khamsin (Egypt), ghibli (Libya), leveche (Spain), Santa Ana (California), loo (north-west India), brickfielder (south-east Australia).
• Hot, turns moist: sirocco (dry over the Sahara, humid by the time it reaches Sicily and Italy).
• Cold, dry: mistral (France), bora (Adriatic).
• Cold, snow-laden: blizzard (North America), purga or buran (Siberia and Central Asia).
• Cold, squally: pampero (Argentina).

Prelims Hooks

• Chinook → eastern slopes of the Rockies (USA and Canada) → "snow eater". Foehn → Alps → helps grapes ripen.
• Zonda = foehn of Argentina (Andes). Norwester = foehn of New Zealand's Canterbury Plains. Neither is a cold wind (trap).
• Foehn winds warm at the dry adiabatic rate (about 10 °C/km) as they descend. Air rising on the windward side cools at the slower wet rate after it becomes saturated.
• Wind → country: Khamsin–Egypt, Ghibli–Libya, Leveche–Spain, Sirocco–Sicily and southern Italy, Harmattan–West Africa.
• Harmattan is a north-easterly, blows November–March, and is called "the doctor". It is dry, not moist (trap).
• Sirocco starts dry but picks up moisture over the Mediterranean and can bring "blood rain".
• Mistral = cold northerly in the Rhône valley (France). Bora = cold wind of the Adriatic. Both are cold, unlike the foehn.
• Purga/Buran → Siberia and Central Asia. Blizzard → North America. Pampero → Argentina.
• Loo = hot, dry westerly over the north-west plains of India in May–June. Brickfielder is the Australian equivalent.
• The Palisades and Eaton fires (7 January 2025, Los Angeles) were driven by Santa Ana winds gusting up to about 100 mph [2][3].

Mains Points

• How relief shapes local winds (GS-I):
• Forced ascent, rain on the windward side and adiabatic warming on the leeward side explain the foehn, chinook, zonda and norwester.
• Funnelling through valleys explains the mistral and bora.

• The same physics creates rain-shadow regions such as the Deccan behind the Western Ghats and Patagonia behind the Andes.

• Effects on economy and livelihoods:

• Helpful: the chinook clears pastures for cattle, and the foehn ripens grapes.
• Harmful: the mistral damages crops, so farmers use cypress windbreaks.

• Mixed: the harmattan brings relief from humid heat but also dust haze, crop stress and disrupted flights.

• Local winds as a disaster driver (GS-III):

• The Santa Ana–driven Los Angeles fires of January 2025 had a chain of causes [2][3]:
  • Wet years grew vegetation.
  • A record-dry season dried it into fuel.
  • Extreme offshore gusts spread the fire.
  • La Niña and warming added to the extreme fire weather.

• In India, the loo drives deadly heatwaves on the north-western plains. This needs heat action plans, early warnings and work-hour changes for outdoor workers.

• Climate change angle:

• Hotter, drier source regions make desert and downslope winds more dangerous: more wildfires, more dust and more heat stress.
• Linking ENSO phases (El Niño and La Niña) to local fire-weather risk is becoming part of disaster preparedness.