Polar Vortex Explained

The setting

Layers of the atmosphere

The air above you is stacked in layers, and the temperature changes direction at every boundary. Weather happens in the bottom one. The polar vortex lives in the next one up.

See it in 3D Where the weather is
75-80%of the atmosphere's mass is in the troposphere, the lowest layer1
99%of its water vapor is there too2
100 km(62 miles) up is the most common definition of where space begins3

The stack

Scientists divide the atmosphere by what the temperature does as you climb. It falls, then rises, then falls, then rises again. Each reversal marks the edge of a layer.

0 km0 mi12 km7.5 mi50 km31 mi85 km53 mi Kármán line, 100 km (62 mi) TroposphereWeather, jet streams, airlinersStratosphereOzone layer, polar vortexMesosphereMeteors burn upThermosphereAuroras, space station 17 °C−51 °C−15 °C−90 °C 500 °C and up colder ← average temperature → warmer
The four lowest layers, to scale with each other, with the average temperature at each boundary.42 The thermosphere continues far above the top of this chart, and a fifth layer, the exosphere, lies beyond it. Boundaries shift with latitude and season, and reference sources differ by a few kilometers.
LayerReaches to aboutTemperature as you climbKnown for
Troposphere12 km (7.5 mi) on averageFallsAlmost all weather
Stratosphere50 km (31 mi)RisesThe ozone layer, the polar vortex
Mesosphere85 km (53 mi)FallsMeteors, the coldest air on Earth
Thermosphere600 km (375 mi)RisesAuroras, the space station
ExosphereNo clear topSatellites; air escaping to space

Troposphere: the weather layer

This is the layer you live in, and almost all weather happens here.4 It holds most of the atmosphere's mass and nearly all of its water vapor.12

Its top, the tropopause, is not at one height. NOAA puts it at 18 to 20 km (11 to 12 miles) at the equator, 9 km (5.5 miles) at 50° latitude, and about 6 km (just under 4 miles) at the poles. It is also lower in winter than in summer.41 A single average is about 12 km (7.5 miles).3

Temperature drops as you go up, from an average of about 17 °C (62 °F) at the ground to about −51 °C (−60 °F) at the tropopause.4

That sloping lid matters for the rest of this site. The jet streams run just beneath it, which is why the subtropical jet is higher than the polar jet.

Stratosphere: calm, dry, and home to the vortex

The stratosphere runs from the tropopause up to about 50 km (31 miles).43 Here the temperature rises with height, from about −51 °C at the bottom to a maximum of about -15 °C (5 °F) at the top.4

The reason is ozone. Ozone is relatively abundant in the stratosphere, and it heats the layer as it absorbs ultraviolet light from the sun. That is the ozone layer, and it is also what shields the surface from that ultraviolet light.53

With warmer air sitting on top of colder air, nothing rises. There is no convection, which is why the flat, anvil-shaped tops of thunderstorms mark the bottom of this layer.4 The stratosphere holds about 19% of the atmosphere's gases and very little water vapor.4

In winter, a ring of strong westerly wind forms in this layer over each pole. That is the polar vortex.

Mesosphere: where meteors burn

From about 50 to 85 km (31 to 53 miles), the temperature falls again.46 The top of this layer is the coldest place in Earth's atmosphere, about −90 °C (−130 °F).2

The air here is thin, but thick enough to slow down meteors, and most of them vaporize in this layer.46

Thermosphere: hot, and nearly empty

Above about 85 km the temperature climbs steeply, because the thin gas absorbs X-rays and ultraviolet light from the sun. In the upper thermosphere it can range from about 500 °C to 2,000 °C or higher.7 You would not feel that heat. The air is so thin that it would feel freezing cold.2

Auroras occur mainly in this layer, and the International Space Station orbits inside it, at 370 to 460 km (about 230 to 285 miles).78 The Kármán line, the most common definition of where space begins, is at 100 km (62 miles).3

Sources put the top of the thermosphere anywhere from 500 to 1,000 km.74

Exosphere: the fade to space

The outermost layer has no clear upper boundary. Atoms and molecules escape into space from here, and satellites orbit in it.94

Where everything on this site happens

Seen from the side, from the equator to the North Pole, the two features this site is about sit at very different heights.

10 km6 mi30 km19 mi50 km31 mi Polar vortexwinter only StratosphereTroposphere Tropopause Subtropical jetPolar jet Equator30°N60°NNorth Pole Warm airCold air
Schematic cross-section. The jet streams run just under the tropopause, which slopes down toward the pole.410 The polar vortex sits far above them in the stratosphere, about 10 to 30 miles up.11
  • Jet streams: in the upper troposphere, roughly 5 to 9 miles (8 to 14 km) up.11
  • Airliners: above 30,000 feet, close to 10 km.12 Depending on the latitude, that is either the top of the troposphere or the bottom of the stratosphere.
  • The polar vortex: in the stratosphere, about 10 to 30 miles (16 to 48 km) up.11 Scientists usually track it at around 19 miles (30 km).13

A matter of scale. Everything up to the top of the mesosphere fits inside 85 km. Earth's radius is 6,371 km,14 so on a globe one foot across, those three layers together would be about 2 millimeters thick. The 3D flyby on this site exaggerates the heights so you can see them.

Sources

  1. UCAR Center for Science Education. The Troposphere.
  2. UCAR Center for Science Education. Layers of Earth's Atmosphere.
  3. NASA Science. Earth's Atmosphere: A Multi-layered Cake.
  4. NOAA National Weather Service, JetStream. Layers of the Atmosphere.
  5. UCAR Center for Science Education. The Stratosphere.
  6. UCAR Center for Science Education. The Mesosphere.
  7. UCAR Center for Science Education. The Thermosphere.
  8. NASA. International Space Station.
  9. UCAR Center for Science Education. The Exosphere.
  10. LibreTexts Geosciences. Atmospheric Processes and Phenomena, 10.6: Jet streams.
  11. NOAA Climate.gov (archived). Understanding the Arctic polar vortex, March 5, 2021.
  12. NASA Goddard Space Flight Center. Stern, D. P., Airplane Flight: How High? How Fast?.
  13. NOAA Climate.gov Polar Vortex Blog (archived). Welcome to the Polar Vortex Blog!, December 5, 2023.
  14. NASA Space Science Data Coordinated Archive. Earth Fact Sheet.

Last updated November 12, 2026