Inversion (meteorology)

Under the right conditions, the normal vertical temperature gradient is inverted so that the air is colder near the surface of the Earth.

This type of inversion occurs in the vicinity of warm fronts, and also in areas of oceanic upwelling such as along the California coast in the United States.

The accumulated smog and dust under the inversion quickly taints the sky reddish, easily seen on sunny days.

The effects are even more pronounced when a city is surrounded by hills or mountains since they form an additional barrier to air circulation.

During a severe inversion, trapped air pollutants form a brownish haze that can cause respiratory problems.

If the layer of cold air near the surface is thick enough, it will lead to the development of ice pellets as the raindrops re-freeze.

Normally this results in distant objects being shortened vertically, an effect that is easy to see at sunset when the sun is visible as an oval.

In an inversion, the normal pattern is reversed, and distant objects are instead stretched out or appear to be above the horizon, leading to the phenomenon known as a Fata Morgana or mirage.

This is noticeable in areas around airports, where the sound of aircraft taking off and landing often can be heard at greater distances around dawn than at other times of day, and inversion thunder which is significantly louder and travels further than when it is produced by lightning strikes under normal conditions.

[10] The shock wave from an explosion can be reflected by an inversion layer in much the same way as it bounces off the ground in an air-burst and can cause additional damage as a result.

Temperature inversion in an urban environment
Temperature inversion in the Lake District
Temperature inversion in the Lake District , England , forms clouds at a low level under clearer air.
Smoke rising in Lochcarron , Scotland , is stopped by an overlying layer of warmer air (2006).
Smog trapped over the city of Almaty , Kazakhstan during a temperature inversion.
Smoke-filled canyons in northern Arizona , 2019. During morning and evening hours, dense smoke often settles in low-lying areas and becomes trapped due to temperature inversions—when a layer within the lower atmosphere acts as a lid and prevents vertical mixing of the air. Steep canyon walls act as a horizontal barrier, concentrating the smoke within the deepest parts of the canyon and increasing the strength of the inversion. [ 1 ]
Height ( y-axis ) versus temperature ( x-axis ) under normal atmospheric conditions (black line). When the layer from 6–8 kilometres (4–5 miles) (designated A-B) descends dry adiabatically , the result is the inversion seen near the ground at 1–2 kilometres (1–1 mile) (C-D).
Klagenfurter Becken ( Austria ) in December 2015: on Mount Goritschnigkogel there is a distinct inverse hoarfrost margin.
A Fata Morgana (or mirage ) of a ship is due to an inversion (2008).
Winter smoke in Shanghai , China , with a clear border-layer for the vertical air-spread (1993).
A temperature inversion in Bratislava , Slovakia , viewing the top of Nový Most (2005).
A valley in low, partially forested mountains seen in wintertime, covered with snow. At the bottom is a village, almost obscured by a layer of grayish-brown air
Inversion-created smog in Nowa Ruda, Poland, 2017
Temperature inversion phenomenon in the early morning near Tawau , Sabah , Malaysia where smoke that was emitted from an oil palm mill stayed close to the ground. The wind carried the smoke in the direction of the nearby settlement to the middle-right of the photo (August 2023).
Mirages due to differing air refractive indices, n