Atmospheric Pressure Belts, Planetary Winds and Jet Streams: Interactive Map and Complete Study Guide

Atmospheric pressure belts, planetary winds and jet streams interactive map and complete study guide covering the equatorial low, subtropical highs, subpolar lows, polar highs, trade winds, westerlies, polar easterlies, Hadley–Ferrel–Polar cells, subtropical and polar-front jet streams, seasonal migration, Rossby waves, western disturbances and the Indian monsoon for UPSC CSE, State PCS, SSC, UGC-NET, AP Geography, school, college, USA and European geography examinations.

IAS NOVA Interactive Atlas

Atmospheric Pressure Belts, Planetary Winds & Jet Streams

Trace Earth’s atmospheric engine—from rising equatorial air and subtropical subsidence to trade winds, roaring westerlies and the fast-moving rivers of air near the tropopause.

7ideal pressure belts
6surface wind belts
3 × 2circulation cells
4+major jet types

Definition

Global atmospheric circulation is the large-scale, three-dimensional movement of air that redistributes heat, moisture and momentum between the equator and the poles. Pressure belts, planetary winds and jet streams are connected parts of this system. The belts shown in textbooks are climatological averages—not fixed, unbroken rings.

Learn with the map: Open it in FULL SCREEN, choose pressure belts, planetary winds, jet streams or circulation cells, switch between Annual Mean, January and July, and hover, tap or use the Index to compare latitude, formation, direction, altitude, weather effects and seasonal migration.

IASNOVA.COM | Geography through mapsGlobal Atmospheric Circulation Interactive Map
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Interactive world map of atmospheric pressure belts, planetary winds and jet streamsA seasonal world circulation map showing pressure belts, trade winds, westerlies, polar easterlies, circulation cells and major jet streams. Hover, focus or tap any feature for details.150°W120°W90°W60°W30°W0°30°E60°E90°E120°E150°E75°S60°S45°S30°S15°S0°EQ15°N30°N45°N60°N75°NNorthern Hadley CellSouthern Hadley CellNorthern Ferrel CellSouthern Ferrel CellNorthern Polar CellSouthern Polar CellEquatorial Low-Pressure Belt / ITCZ — Usually near 5°S–5°N over oceans; migrates farther over continentsNorthern Subtropical High-Pressure Belt — About 25°–35°N in the annual meanSouthern Subtropical High-Pressure Belt — About 25°–35°S in the annual meanNorthern Subpolar Low-Pressure Belt — Broadly around 50°–70°N; strongest and farthest south in winterSouthern Subpolar Low-Pressure Belt — Broadly around 50°–70°SNorth Polar High — High Arctic, approximately 75°–90°N in the ideal modelSouth Polar High — Antarctica, approximately 75°–90°S in the ideal modelNortheast Trade Winds — Between the northern subtropical high and the ITCZNortheast Trade Winds — Between the northern subtropical high and the ITCZNortheast Trade Winds — Between the northern subtropical high and the ITCZNortheast Trade Winds — Between the northern subtropical high and the ITCZNortheast Trade Winds — Between the northern subtropical high and the ITCZNortheast Trade Winds — Between the northern subtropical high and the ITCZSoutheast Trade Winds — Between the southern subtropical high and the ITCZSoutheast Trade Winds — Between the southern subtropical high and the ITCZSoutheast Trade Winds — Between the southern subtropical high and the ITCZSoutheast Trade Winds — Between the southern subtropical high and the ITCZSoutheast Trade Winds — Between the southern subtropical high and the ITCZSoutheast Trade Winds — Between the southern subtropical high and the ITCZNorthern Hemisphere Westerlies — Mid-latitudes between subtropical highs and subpolar lowsNorthern Hemisphere Westerlies — Mid-latitudes between subtropical highs and subpolar lowsNorthern Hemisphere Westerlies — Mid-latitudes between subtropical highs and subpolar lowsNorthern Hemisphere Westerlies — Mid-latitudes between subtropical highs and subpolar lowsNorthern Hemisphere Westerlies — Mid-latitudes between subtropical highs and subpolar lowsNorthern Hemisphere Westerlies — Mid-latitudes between subtropical highs and subpolar lowsSouthern Hemisphere Westerlies — Mid-latitudes of the Southern HemisphereSouthern Hemisphere Westerlies — Mid-latitudes of the Southern HemisphereSouthern Hemisphere Westerlies — Mid-latitudes of the Southern HemisphereSouthern Hemisphere Westerlies — Mid-latitudes of the Southern HemisphereSouthern Hemisphere Westerlies — Mid-latitudes of the Southern HemisphereSouthern Hemisphere Westerlies — Mid-latitudes of the Southern HemisphereNorthern Polar Easterlies — From the Arctic polar high toward the subpolar lowNorthern Polar Easterlies — From the Arctic polar high toward the subpolar lowNorthern Polar Easterlies — From the Arctic polar high toward the subpolar lowNorthern Polar Easterlies — From the Arctic polar high toward the subpolar lowNorthern Polar Easterlies — From the Arctic polar high toward the subpolar lowNorthern Polar Easterlies — From the Arctic polar high toward the subpolar lowSouthern Polar Easterlies — From the Antarctic polar high toward the circumpolar troughSouthern Polar Easterlies — From the Antarctic polar high toward the circumpolar troughSouthern Polar Easterlies — From the Antarctic polar high toward the circumpolar troughSouthern Polar Easterlies — From the Antarctic polar high toward the circumpolar troughSouthern Polar Easterlies — From the Antarctic polar high toward the circumpolar troughSouthern Polar Easterlies — From the Antarctic polar high toward the circumpolar troughNorthern Subtropical Westerly Jet — Usually near 20°–30° latitude and roughly 12–14 km altitudeSouthern Subtropical Westerly Jet — Near 20°–30°S, commonly close to the tropical tropopauseNorthern Polar-Front Jet — Commonly near 45°–65°N around the tropopause, roughly 8–12 kmSouthern Polar-Front Jet — Mid- to high-latitude tropopause over the Southern OceanTropical Easterly Jet — Upper troposphere, commonly near 100–200 hPa during Northern Hemisphere summerNorthern Polar-Night Jet — Stratosphere around the winter polar vortexSouthern Polar-Night Jet — Stratosphere around the Antarctic winter vortexNorthern Hadley CellSouthern Hadley CellNorthern Ferrel CellSouthern Ferrel CellNorthern Polar CellSouthern Polar CellEquatorial Low-Pressure Belt / ITCZSubtropical High-Pressure BeltSubtropical High-Pressure BeltSubpolar Low-Pressure BeltSubpolar Low-Pressure BeltNorth Polar HighSouth Polar HighNortheast Trade WindsSoutheast Trade WindsNorthern Hemisphere WesterliesSouthern Hemisphere WesterliesNorthern Polar EasterliesSouthern Polar EasterliesNorthern Subtropical Westerly JetSouthern Subtropical Westerly JetNorthern Polar-Front JetSouthern Polar-Front JetTropical Easterly JetNorthern Polar-Night JetSouthern Polar-Night JetNorthern Hadley CellSouthern Hadley CellNorthern Ferrel CellSouthern Ferrel CellNorthern Polar CellSouthern Polar CellEquatorial Low-Pressure Belt / ITCZ — Usually near 5°S–5°N over oceans; migrates farther over continentsNorthern Subtropical High-Pressure Belt — About 25°–35°N in the annual meanSouthern Subtropical High-Pressure Belt — About 25°–35°S in the annual meanNorthern Subpolar Low-Pressure Belt — Broadly around 50°–70°N; strongest and farthest south in winterSouthern Subpolar Low-Pressure Belt — Broadly around 50°–70°SNorth Polar High — High Arctic, approximately 75°–90°N in the ideal modelSouth Polar High — Antarctica, approximately 75°–90°S in the ideal modelNortheast Trade Winds — Between the northern subtropical high and the ITCZNortheast Trade Winds — Between the northern subtropical high and the ITCZNortheast Trade Winds — Between the northern subtropical high and the ITCZNortheast Trade Winds — Between the northern subtropical high and the ITCZNortheast Trade Winds — Between the northern subtropical high and the ITCZNortheast Trade Winds — Between the northern subtropical high and the ITCZSoutheast Trade Winds — Between the southern subtropical high and the ITCZSoutheast Trade Winds — Between the southern subtropical high and the ITCZSoutheast Trade Winds — Between the southern subtropical high and the ITCZSoutheast Trade Winds — Between the southern subtropical high and the ITCZSoutheast Trade Winds — Between the southern subtropical high and the ITCZSoutheast Trade Winds — Between the southern subtropical high and the ITCZNorthern Hemisphere Westerlies — Mid-latitudes between subtropical highs and subpolar lowsNorthern Hemisphere Westerlies — Mid-latitudes between subtropical highs and subpolar lowsNorthern Hemisphere Westerlies — Mid-latitudes between subtropical highs and subpolar lowsNorthern Hemisphere Westerlies — Mid-latitudes between subtropical highs and subpolar lowsNorthern Hemisphere Westerlies — Mid-latitudes between subtropical highs and subpolar lowsNorthern Hemisphere Westerlies — Mid-latitudes between subtropical highs and subpolar lowsSouthern Hemisphere Westerlies — Mid-latitudes of the Southern HemisphereSouthern Hemisphere Westerlies — Mid-latitudes of the Southern HemisphereSouthern Hemisphere Westerlies — Mid-latitudes of the Southern HemisphereSouthern Hemisphere Westerlies — Mid-latitudes of the Southern HemisphereSouthern Hemisphere Westerlies — Mid-latitudes of the Southern HemisphereSouthern Hemisphere Westerlies — Mid-latitudes of the Southern HemisphereNorthern Polar Easterlies — From the Arctic polar high toward the subpolar lowNorthern Polar Easterlies — From the Arctic polar high toward the subpolar lowNorthern Polar Easterlies — From the Arctic polar high toward the subpolar lowNorthern Polar Easterlies — From the Arctic polar high toward the subpolar lowNorthern Polar Easterlies — From the Arctic polar high toward the subpolar lowNorthern Polar Easterlies — From the Arctic polar high toward the subpolar lowSouthern Polar Easterlies — From the Antarctic polar high toward the circumpolar troughSouthern Polar Easterlies — From the Antarctic polar high toward the circumpolar troughSouthern Polar Easterlies — From the Antarctic polar high toward the circumpolar troughSouthern Polar Easterlies — From the Antarctic polar high toward the circumpolar troughSouthern Polar Easterlies — From the Antarctic polar high toward the circumpolar troughSouthern Polar Easterlies — From the Antarctic polar high toward the circumpolar troughNorthern Subtropical Westerly Jet — Usually near 20°–30° latitude and roughly 12–14 km altitudeSouthern Subtropical Westerly Jet — Near 20°–30°S, commonly close to the tropical tropopauseNorthern Polar-Front Jet — Commonly near 45°–65°N around the tropopause, roughly 8–12 kmSouthern Polar-Front Jet — Mid- to high-latitude tropopause over the Southern OceanNorthern Polar-Night Jet — Stratosphere around the winter polar vortexNorthern Hadley CellSouthern Hadley CellNorthern Ferrel CellSouthern Ferrel CellNorthern Polar CellSouthern Polar CellEquatorial Low-Pressure Belt / ITCZSubtropical High-Pressure BeltSubtropical High-Pressure BeltSubpolar Low-Pressure BeltSubpolar Low-Pressure BeltNorth Polar HighSouth Polar HighNortheast Trade WindsSoutheast Trade WindsNorthern Hemisphere WesterliesSouthern Hemisphere WesterliesNorthern Polar EasterliesSouthern Polar EasterliesNorthern Subtropical Westerly JetSouthern Subtropical Westerly JetNorthern Polar-Front JetSouthern Polar-Front JetNorthern Polar-Night JetNorthern Hadley CellSouthern Hadley CellNorthern Ferrel CellSouthern Ferrel CellNorthern Polar CellSouthern Polar CellEquatorial Low-Pressure Belt / ITCZ — Usually near 5°S–5°N over oceans; migrates farther over continentsNorthern Subtropical High-Pressure Belt — About 25°–35°N in the annual meanSouthern Subtropical High-Pressure Belt — About 25°–35°S in the annual meanNorthern Subpolar Low-Pressure Belt — Broadly around 50°–70°N; strongest and farthest south in winterSouthern Subpolar Low-Pressure Belt — Broadly around 50°–70°SNorth Polar High — High Arctic, approximately 75°–90°N in the ideal modelSouth Polar High — Antarctica, approximately 75°–90°S in the ideal modelNortheast Trade Winds — Between the northern subtropical high and the ITCZNortheast Trade Winds — Between the northern subtropical high and the ITCZNortheast Trade Winds — Between the northern subtropical high and the ITCZNortheast Trade Winds — Between the northern subtropical high and the ITCZNortheast Trade Winds — Between the northern subtropical high and the ITCZNortheast Trade Winds — Between the northern subtropical high and the ITCZSoutheast Trade Winds — Between the southern subtropical high and the ITCZSoutheast Trade Winds — Between the southern subtropical high and the ITCZSoutheast Trade Winds — Between the southern subtropical high and the ITCZSoutheast Trade Winds — Between the southern subtropical high and the ITCZSoutheast Trade Winds — Between the southern subtropical high and the ITCZSoutheast Trade Winds — Between the southern subtropical high and the ITCZNorthern Hemisphere Westerlies — Mid-latitudes between subtropical highs and subpolar lowsNorthern Hemisphere Westerlies — Mid-latitudes between subtropical highs and subpolar lowsNorthern Hemisphere Westerlies — Mid-latitudes between subtropical highs and subpolar lowsNorthern Hemisphere Westerlies — Mid-latitudes between subtropical highs and subpolar lowsNorthern Hemisphere Westerlies — Mid-latitudes between subtropical highs and subpolar lowsNorthern Hemisphere Westerlies — Mid-latitudes between subtropical highs and subpolar lowsSouthern Hemisphere Westerlies — Mid-latitudes of the Southern HemisphereSouthern Hemisphere Westerlies — Mid-latitudes of the Southern HemisphereSouthern Hemisphere Westerlies — Mid-latitudes of the Southern HemisphereSouthern Hemisphere Westerlies — Mid-latitudes of the Southern HemisphereSouthern Hemisphere Westerlies — Mid-latitudes of the Southern HemisphereSouthern Hemisphere Westerlies — Mid-latitudes of the Southern HemisphereNorthern Polar Easterlies — From the Arctic polar high toward the subpolar lowNorthern Polar Easterlies — From the Arctic polar high toward the subpolar lowNorthern Polar Easterlies — From the Arctic polar high toward the subpolar lowNorthern Polar Easterlies — From the Arctic polar high toward the subpolar lowNorthern Polar Easterlies — From the Arctic polar high toward the subpolar lowNorthern Polar Easterlies — From the Arctic polar high toward the subpolar lowSouthern Polar Easterlies — From the Antarctic polar high toward the circumpolar troughSouthern Polar Easterlies — From the Antarctic polar high toward the circumpolar troughSouthern Polar Easterlies — From the Antarctic polar high toward the circumpolar troughSouthern Polar Easterlies — From the Antarctic polar high toward the circumpolar troughSouthern Polar Easterlies — From the Antarctic polar high toward the circumpolar troughSouthern Polar Easterlies — From the Antarctic polar high toward the circumpolar troughNorthern Subtropical Westerly Jet — Usually near 20°–30° latitude and roughly 12–14 km altitudeSouthern Subtropical Westerly Jet — Near 20°–30°S, commonly close to the tropical tropopauseNorthern Polar-Front Jet — Commonly near 45°–65°N around the tropopause, roughly 8–12 kmSouthern Polar-Front Jet — Mid- to high-latitude tropopause over the Southern OceanTropical Easterly Jet — Upper troposphere, commonly near 100–200 hPa during Northern Hemisphere summerSouthern Polar-Night Jet — Stratosphere around the Antarctic winter vortexNorthern Hadley CellSouthern Hadley CellNorthern Ferrel CellSouthern Ferrel CellNorthern Polar CellSouthern Polar CellEquatorial Low-Pressure Belt / ITCZSubtropical High-Pressure BeltSubtropical High-Pressure BeltSubpolar Low-Pressure BeltSubpolar Low-Pressure BeltNorth Polar HighSouth Polar HighNortheast Trade WindsSoutheast Trade WindsNorthern Hemisphere WesterliesSouthern Hemisphere WesterliesNorthern Polar EasterliesSouthern Polar EasterliesNorthern Subtropical Westerly JetSouthern Subtropical Westerly JetNorthern Polar-Front JetSouthern Polar-Front JetTropical Easterly JetSouthern Polar-Night JetIASNOVA.COMIASNOVA.COMIASNOVA.COMIASNOVA.COMIASNOVA.COMIASNOVA.COM
Annual-mean teaching view. Belts are broad, migrating zones rather than fixed lines.January teaching view. Circulation shifts toward the Southern Hemisphere summer, while Northern Hemisphere jets and storm tracks move equatorward.July teaching view. Circulation shifts northward, the Tropical Easterly Jet develops over the Afro-Asian monsoon sector, and northern jets retreat poleward.
01 | Atmospheric engine

Why the atmosphere circulates

Earth receives much more solar energy in the tropics than near the poles. If the atmosphere and oceans did not transfer heat, equatorial regions would become progressively hotter and polar regions colder. Global circulation is the atmosphere’s heat-redistribution system.

1. Unequal heatingCurvature, axial tilt, seasons, clouds, albedo and land–water contrasts create temperature differences.
2. Pressure gradientsWarm columns expand and cold columns contract, generating horizontal and vertical pressure differences.
3. Air acceleratesThe pressure-gradient force starts air moving from higher toward lower pressure.
4. Rotation deflectsCoriolis turns motion right in the north and left in the south; it is zero at the equator.
5. Friction modifiesNear the surface, friction slows wind and makes it cross isobars toward low pressure.
6. Eddies transfer heatCyclones, anticyclones, waves and jets transport heat and momentum, especially in mid-latitudes.
Pressure is not simply “hot = low” everywhere. Surface heating can create a thermal low, but subtropical highs and subpolar lows are strongly dynamic products of large-scale convergence, divergence and vertical motion. Pressure also changes with altitude, so surface and upper-air pressure patterns must be distinguished.

Forces controlling wind

Pressure-gradient force

Starts the wind

Acts from high pressure toward low pressure and becomes stronger where isobars are closely spaced. It is the only major horizontal force that can start air from rest.

Coriolis effect

Turns the moving air

Acts perpendicular to motion: right in the Northern Hemisphere and left in the Southern Hemisphere. It increases with latitude and wind speed and vanishes at the equator.

Friction

Matters near the surface

Slows wind, weakens Coriolis deflection and makes surface air spiral into lows and out of highs. Its influence rapidly decreases above the planetary boundary layer.

Curvature and gravity

Shape three-dimensional flow

Centrifugal effects matter around curved paths, while gravity balances the vertical pressure-gradient force through hydrostatic equilibrium.

02 | Three-cell model

Hadley, Ferrel and Polar circulation cells

The idealised model divides each hemisphere into three broad cells. It is most useful as a long-term zonal mean. Continents, oceans, mountains, seasonal heating and transient weather systems make the real atmosphere far more complex.

90°S 60°S 30°S 0° 30°N 60°N 90°N HadleyHadleyFerrelFerrelPolarPolar RISING ITCZ · EQUATORIAL LOW SINKING SUBTROPICAL HIGH SINKING SUBTROPICAL HIGH RISING SUBPOLAR LOW RISING SUBPOLAR LOW
CellApproximate latitudeThermal characterSurface windMain climatic expression
Hadley0°–30°Direct: warm air rises, cooler air sinksTrade windsEquatorial rain belt and subtropical dry belts
Ferrel30°–60°Indirect and eddy-drivenWesterliesTemperate cyclones, fronts and variable weather
Polar60°–90°Direct but weakPolar easterliesPolar cold, dryness and the polar-front boundary
03 | Pressure belts

The seven idealised atmospheric pressure belts

In the ideal model, Earth has one equatorial low, two subtropical highs, two subpolar lows and two polar highs. In reality these zones vary in width and intensity and are broken into semi-permanent and seasonal pressure cells.

0° · thermal low

Equatorial low / ITCZ

Process: intense heating, moisture convergence and deep convection.

Weather: cloud towers, thunderstorms, heavy rain and weak variable surface winds.

Migration: toward the summer hemisphere; much farther over continents than oceans.

25°–35° · dynamic high

Subtropical highs

Process: descending air in the poleward limb of the Hadley circulation.

Weather: stable, dry, often cloud-free conditions and light winds near horse latitudes.

Climate link: hot deserts and dry west coasts; source of trades and westerlies.

50°–70° · dynamic low

Subpolar lows

Process: convergence near the polar front and frequent mid-latitude cyclogenesis.

Weather: frontal cloud, storms, strong winds and frequent precipitation.

Examples: Icelandic and Aleutian lows; circumpolar Southern Ocean trough.

75°–90° · thermal high

Polar highs

Process: radiational cooling produces cold dense descending air.

Weather: very cold and dry; source region of polar easterlies.

Reality check: mobile cyclones and topography frequently disrupt the ideal belt.

Why pressure belts are discontinuous

  • Land–sea thermal contrast: continents heat and cool faster than oceans, generating summer lows and winter highs.
  • Relief: the Tibetan Plateau, Rockies, Andes and other mountains alter temperature, pressure and planetary waves.
  • Ocean currents: warm and cold currents change lower-atmospheric stability and the strength of oceanic highs and lows.
  • Seasonal migration: the thermal equator and circulation cells shift north and south through the year.
  • Mobile weather systems: cyclones and anticyclones continually disturb the climatological mean.
04 | Planetary winds

Trade winds, westerlies and polar easterlies

Planetary or permanent winds are prevailing surface winds produced by the global pressure-gradient pattern and modified by Earth’s rotation. “Permanent” means persistent in the long-term mean, not unchanging every day.

Wind beltSource → destinationNorthern HemisphereSouthern HemisphereMajor effects
Trade windsSubtropical highs → ITCZNortheast tradesSoutheast tradesTropical convergence, ocean gyres, tropical cyclone steering, upwelling and monsoonal cross-equatorial flow
WesterliesSubtropical highs → subpolar lowsMostly southwest to northeastMostly northwest to southeastEastward movement of temperate cyclones, fronts and ocean currents
Polar easterliesPolar highs → subpolar lowsNortheast to southwestSoutheast to northwestCold-air transport and convergence at the polar front

Calm or variable-wind zones

  • Doldrums: weak horizontal pressure gradient and rising air near the ITCZ; calm spells alternate with intense squalls.
  • Horse latitudes: subsiding air and weak gradients near subtropical highs; dry, stable conditions are common.

Named Southern Ocean westerlies

  • Roaring Forties: strong westerlies around 40°S.
  • Furious Fifties: stronger and stormier near 50°S.
  • Screaming Sixties: powerful circumpolar winds closer to Antarctica.
Wind direction convention: a westerly wind comes from the west and blows toward the east. An easterly comes from the east and blows westward. This convention is frequently tested.
05 | Jet streams

Fast rivers of air near the tropopause

Jet streams are narrow, elongated cores of very strong wind, usually near the tropopause. Most major jets flow west to east, but their latitude, altitude, speed and waviness change continuously. They form where strong horizontal temperature gradients produce strong vertical wind shear and where upper-air momentum is concentrated.

Mid- to high latitudes

Polar-front jet

Location: usually 45°–65°, around 8–12 km, but highly variable.

Cause: strong temperature contrast across the polar front.

Role: steers depressions and fronts; jet streak divergence can deepen surface lows.

Season: stronger and farther equatorward in winter.

Subtropical upper troposphere

Subtropical westerly jet

Location: commonly 20°–30°, near 12–14 km.

Cause: poleward upper-level flow from the Hadley cell conserves angular momentum.

Role: influences subtropical weather and winter disturbances.

Season: stronger and equatorward in winter, poleward in summer.

Boreal summer easterly

Tropical easterly jet

Location: upper troposphere over Africa, Indian Ocean and South Asia.

Cause: summer heating of Asia and the Tibetan Plateau reverses the upper-level gradient.

Role: associated with mature monsoon circulation and tropical convection.

Direction: east to west—unlike the main westerly jets.

Winter stratosphere

Polar-night jet

Location: around the winter polar vortex in the stratosphere.

Cause: intense temperature contrast between the dark winter pole and lower latitudes.

Role: linked with sudden stratospheric warming and polar-vortex variability.

Distinction: not the same as the tropospheric polar-front jet.

Jet-stream vocabulary

  • Jet core: zone of maximum wind speed.
  • Jet streak: a local speed maximum within a jet.
  • Ridge: poleward bulge in the westerly flow.
  • Trough: equatorward dip that often supports unsettled weather.
  • Zonal flow: relatively straight west-to-east path; weather systems move quickly.
  • Meridional flow: large north–south meanders; weather patterns may persist.
  • Rossby waves: planetary-scale waves shaped by rotation and the latitude variation of Coriolis.
  • Blocking: persistent high-amplitude pattern that slows or diverts normal storm tracks.
06 | Seasonal migration

Why the belts move in January and July

The zone of maximum heating moves with the apparent position of the Sun, but the atmospheric response lags and is modified by thermal inertia. Pressure belts, winds and jets therefore migrate toward the summer hemisphere and back toward the winter hemisphere.

  1. January: the thermal equator lies mainly south of the geographic equator. Northern jets strengthen and move equatorward; austral belts shift poleward.
  2. July: the ITCZ moves north, especially over South and East Asia and Africa. The Northern subtropical westerly jet retreats poleward, while the tropical easterly jet develops over the Afro-Asian monsoon sector.
  3. Oceans versus continents: oceanic belts move only a few degrees, while continental convergence zones may travel much farther because land heats and cools rapidly.
  4. Topographic forcing: elevated plateaus behave as large heat sources in summer and cold sources in winter, profoundly modifying the simple zonal pattern.

Seasonal-shift rule for answers

Write that pressure and wind belts shift toward the summer hemisphere, but immediately add that the shift is larger over continents, smaller over oceans and strongly modified by topography. This avoids the common error of treating every belt as a rigid line.

07 | India focus

Pressure belts, jets and the Indian monsoon

The Indian monsoon is a regional expression of planetary circulation modified by the Asian continent, the Indian Ocean, the Himalaya and the Tibetan Plateau.

Summer surface circulation

Northward ITCZ and monsoon trough

Intense heating creates low pressure over northwestern India and the Tibetan–Asian region. The ITCZ shifts north and appears over the subcontinent as the monsoon trough.

Cross-equatorial inflow

Southeast trades become southwesterlies

Air from the southern Indian Ocean subtropical high crosses the equator. Coriolis deflects it to the right in the Northern Hemisphere, creating the southwesterly monsoon flow.

Upper-level transition

Subtropical westerly jet retreats north

During winter the subtropical westerly jet lies south of the Himalaya and helps guide western disturbances. Its northward shift is part of the summer circulation reorganisation.

Summer upper air

Tropical easterly jet develops

An upper-level easterly jet forms south of the Tibetan anticyclone and is associated with the mature monsoon circulation over South Asia and the northern Indian Ocean.

Western disturbances

Western disturbances are eastward-moving extratropical systems embedded in the subtropical westerlies. They bring winter rain to northwestern India and snow to the western Himalaya, supporting rabi agriculture but also causing floods, hail and avalanches when unusually strong.

Somali jet and low-level monsoon flow

A strong cross-equatorial low-level current develops near East Africa and the Arabian Sea during boreal summer. It transports moisture toward India and interacts with the Western Ghats, Arabian Sea branch and monsoon depressions. It is a low-level jet and should not be confused with the upper-tropospheric tropical easterly jet.

08 | Climate connections

How global circulation shapes world climates

Circulation zoneVertical motionTypical climateRepresentative regionsKey hazards
ITCZ / equatorial lowStrong ascentHot, humid, frequent convectionAmazon, Congo, Maritime Southeast AsiaThunderstorms, floods, lightning
Subtropical highsSubsidenceArid or semi-arid; stable eastern ocean marginsSahara, Arabian, Atacama, Namib, AustraliaDrought, heat, dust, wildfire
Westerly belt / polar frontAlternating ascent and descentTemperate and highly variableEurope, North America, southern Chile, New ZealandExtratropical storms, cold waves, floods
Polar highsSubsidenceVery cold and dryAntarctica, Greenland interior, high ArcticBlizzards, katabatic winds, extreme cold
Jet-stream ridges and troughsUpper-air divergence/convergence variesControls storm-track position and persistenceMid-latitudes worldwideBlocking heatwaves, prolonged rain, cold outbreaks

Ocean connections

Planetary winds drive the major surface-ocean gyres, contribute to equatorial and coastal upwelling, and help redistribute heat. Trade winds pile warm water westward in tropical oceans; changes in these winds are central to ENSO and Walker-circulation variability. Westerlies drive eastward currents and the powerful Antarctic Circumpolar Current.

09 | Comparison and misconceptions

High-yield distinctions for examinations

PairCorrect distinction
Pressure belt vs pressure centreA belt is a broad climatological latitudinal zone; a centre is a regional high or low such as the Icelandic Low or Azores High.
Thermal vs dynamic pressureThermal pressure arises mainly from heating/cooling of air columns; dynamic pressure arises from large-scale convergence, divergence and vertical motion.
Surface wind vs jet streamPlanetary winds are lower-tropospheric prevailing flows; jet streams are narrow high-speed currents near the tropopause or in the stratosphere.
Polar-front jet vs polar-night jetThe polar-front jet is tropospheric and linked to mid-latitude temperature gradients; the polar-night jet is stratospheric and linked to the winter polar vortex.
Tropical easterly jet vs Somali jetTEJ is an upper-tropospheric easterly; the Somali jet is a low-level southwesterly monsoon current.
Three-cell model vs real atmosphereThe model is a zonal and long-term average; real circulation includes longitudinal cells, monsoons, stationary waves and transient weather systems.

Common mistakes

  • Writing that pressure belts remain at exact latitudes throughout the year.
  • Saying Coriolis creates wind; pressure-gradient force starts wind, while Coriolis deflects moving air.
  • Drawing southwest trades in the Southern Hemisphere; they are southeast trades before crossing the equator.
  • Calling every high-altitude wind a jet stream.
  • Confusing the tropical easterly jet with low-level monsoon winds.
  • Showing the Ferrel cell as a simple thermally driven convection loop.
10 | Complete reference

Latitude-by-latitude revision framework

90°–60°

Polar domain

Surface pressure: polar high to subpolar low.

Surface wind: polar easterlies.

Cell: Polar cell.

Upper air: polar-front jet near the boundary; polar-night jet in winter stratosphere.

60°–30°

Mid-latitude domain

Surface pressure: subtropical high to subpolar low.

Surface wind: westerlies.

Cell: Ferrel cell.

Weather: fronts, cyclones, anticyclones and jet-controlled storm tracks.

30°–0°

Tropical domain

Surface pressure: subtropical high to equatorial low.

Surface wind: trades.

Cell: Hadley cell.

Upper air: subtropical jet; tropical easterly jet regionally in boreal summer.

Near 0°

Equatorial convergence

Feature: ITCZ / doldrums.

Motion: convergence and ascent.

Weather: deep convection and heavy rainfall.

Seasonality: migration creates many tropical wet and dry seasons.

11 | Test yourself

MCQs with explanations

Answer each question before opening its explanation. This format remains fully functional even when WordPress blocks JavaScript.

1. Which pressure belt is primarily produced by intense surface heating and rising air?

  1. Subtropical high
  2. Equatorial low / ITCZ
  3. Subpolar low
  4. Polar high
Show answer and explanation

B. Equatorial low / ITCZ

The equatorial low is mainly thermal: strong heating, convergence and convection cause air to rise.

2. Why do the northeast trade winds have an easterly component?

  1. Friction turns them eastward
  2. Coriolis deflects equatorward flow to the right in the Northern Hemisphere
  3. They originate at the polar front
  4. Jet streams pull them westward
Show answer and explanation

B. Coriolis deflects equatorward flow to the right in the Northern Hemisphere

Air moves from the subtropical high toward the equatorial low and is deflected right, producing a northeast-to-southwest flow.

3. The Ferrel cell is best described as:

  1. A direct tropical thermal cell
  2. A thermally indirect, eddy-driven mid-latitude mean circulation
  3. A stratospheric circulation only
  4. A local sea-breeze cell
Show answer and explanation

B. A thermally indirect, eddy-driven mid-latitude mean circulation

The Ferrel cell is maintained largely by mid-latitude weather systems and eddy heat/momentum transport.

4. Which belt is closely associated with the world’s major hot deserts?

  1. Equatorial low
  2. Subtropical high
  3. Subpolar low
  4. Polar front
Show answer and explanation

B. Subtropical high

Subsiding stable air near the subtropical highs suppresses clouds and rainfall, favouring arid climates.

5. The polar-front jet is strongest when:

  1. The equator-to-pole temperature gradient is weak
  2. The horizontal temperature gradient is strong, usually in winter
  3. Surface friction is strongest
  4. The ITCZ is exactly on the equator
Show answer and explanation

B. The horizontal temperature gradient is strong, usually in winter

A stronger horizontal temperature gradient produces stronger vertical wind shear and a more powerful upper-level jet.

6. Which jet is characteristically easterly?

  1. Polar-front jet
  2. Subtropical westerly jet
  3. Tropical easterly jet
  4. Polar-night jet
Show answer and explanation

C. Tropical easterly jet

The tropical easterly jet develops over the Afro-Asian monsoon sector in boreal summer and flows east to west.

7. Why are Southern Hemisphere westerlies especially strong and continuous?

  1. The Coriolis effect is absent
  2. There is little land obstruction across the Southern Ocean
  3. The polar high is always weak
  4. They blow within the tropics
Show answer and explanation

B. There is little land obstruction across the Southern Ocean

Long oceanic fetch and limited continental interruption support the powerful Roaring Forties and related belts.

8. During Northern Hemisphere summer, the global pressure and wind belts generally shift:

  1. Toward the south
  2. Toward the north, especially over continents
  3. Only vertically
  4. They do not shift
Show answer and explanation

B. Toward the north, especially over continents

The thermal equator and associated circulation migrate toward the warmer summer hemisphere, with larger shifts over land.

9. In India, winter western disturbances are commonly steered by the:

  1. Tropical easterly jet
  2. Subtropical westerly jet
  3. Southeast trades
  4. Polar easterlies at the surface
Show answer and explanation

B. Subtropical westerly jet

The subtropical westerly jet and embedded troughs help guide western disturbances across West and South Asia.

10. Which statement about pressure belts is most accurate?

  1. They are fixed, continuous rings at exact latitudes
  2. They are climatological zones broken and displaced by seasons, land–sea contrast and relief
  3. They occur only over oceans
  4. They are identical at the surface and aloft
Show answer and explanation

B. They are climatological zones broken and displaced by seasons, land–sea contrast and relief

Textbook belts are idealised annual means. Real pressure fields contain semi-permanent cells, mobile systems and strong seasonal displacement.

12 | FAQs

Frequently asked questions

Why are there seven pressure belts but six wind belts?

The equatorial low is shared by both hemispheres. Surface winds occupy the zones between adjacent pressure belts: three wind belts in each hemisphere, giving six in total.

Are the pressure belts located exactly at 0°, 30°, 60° and 90°?

No. These are teaching latitudes. Actual belts are broad, irregular, seasonal and broken into cells by land–sea contrast, relief, ocean currents and weather systems.

Why are subtropical highs called dynamic highs?

They are produced mainly by descending air and upper-level mass convergence in the Hadley circulation rather than simply by local surface cooling.

Why are subpolar lows especially strong in winter?

Winter strengthens the equator-to-pole temperature contrast, the polar-front jet and mid-latitude cyclogenesis. Northern semi-permanent lows such as the Icelandic and Aleutian lows deepen.

Why is the Southern Hemisphere westerly belt stronger?

The Southern Ocean provides a nearly uninterrupted circumpolar path. Continents and major mountain barriers disrupt the Northern Hemisphere westerlies much more strongly.

Do jet streams cause surface weather?

They do not act alone, but their position, curvature and local acceleration strongly influence upper-level divergence, surface pressure development, cyclone tracks and the persistence of weather regimes.

Why do jets move equatorward in winter?

The strongest horizontal temperature gradient also shifts equatorward, and winter cooling increases the contrast between tropical and polar air, usually strengthening the jet.

How are pressure belts connected with monsoons?

Seasonal heating shifts and breaks the planetary pressure pattern. Cross-equatorial pressure gradients reverse lower-level winds, while seasonal changes in upper-air jets help organise monsoon onset, strength and withdrawal.

Is the ITCZ the same as the thermal equator?

They are related but not identical. The thermal equator is the zone of highest mean temperature; the ITCZ is a convergence and convection zone influenced by sea-surface temperature, land heating, moisture and atmospheric dynamics.

What is the easiest way to remember the sequence from equator to pole?

Use: Low–High–Low–High for pressure, Trades–Westerlies–Polar easterlies for surface winds, and Hadley–Ferrel–Polar for cells.

13 | Sources

Authoritative references and further reading

Cartographic note: all belt limits, arrows and jet paths are educational generalisations. Actual atmospheric features vary daily, seasonally and regionally.

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IAS NOVA Editorial Team
IAS NOVA Editorial Team
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