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When you read about temperature inversions online, you mostly hear about them trapping pollution in places like Salt Lake City, which is surrounded by mountains. That seems to be the case for most other cities with inversion-related pollution problems, like those in California or China. Clearly the natural barrier of mountains helps trap the cap of warmer air over the cooler air by preventing it from dispersing to the side.

Is it possible for a surface temperature inversion to form in areas with a different type of topography? What conditions would need to be in place in order for a surface temperature inversion to occur outside of a valley or natural bowl?

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  • $\begingroup$ I edited your question to make it clear you are asking about surface temperature inversions... not upper air inversions. I also removed the secondary question of frequency because it is too broad. $\endgroup$
    – f.thorpe
    Dec 11 '21 at 16:59
  • $\begingroup$ @Empiromancer One reason is probably that a common cause of temperature inversions is when masses of cold air are moving from mountains down to valleys during the night. But other common causes of temperature inversions can theoretically occur in other topographies too (e.g. coastal areas). $\endgroup$
    – Pat
    Dec 12 '21 at 13:44
  • $\begingroup$ There is possible also radiative and advective surface inversion in flat orography. Note that maintains not only keep cold air between them, but actively supply the cold air due radiative cooling and cold air flow downhill to the valley bottom. $\endgroup$
    – Poutnik
    Jan 9 at 9:40
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Valleys and basins make surface temperature inversions (STI) easier to form and harder to disperse. However, an STI is the result of warm air sitting above colder air can form independently of orographic constraints:

Turbulence Inversion: A poorly understood stratification of warm air over colder air when very light wind eddies fail to interact and vertically mix with surface air. These can form over flat, non-mountainous terrain.

Frontal Inversion: A large, cold air mass wedges itself under a stable high pressure system; these are more related to fast moving, unstable weather systems. On that note, continental scale weather systems may also produce...

Subsidence Inversion: Forms when a descending high-pressure system compresses an air mass far enough to cool it relative to the mass above.

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One other possible source of surface temperature inversions involves bodies of water.

On an unusually warm spring day in, let us say, Chicago, the air temperature is inherently warmer than the temperature of the Lake Michigan water below, which is still relatively cool from the preceding winter. So the water absorbs heat from the overlying air, creating a cool layer. Voila, a surface temperature inversion.

The effect can be strong enough to capture pollution and create a dark layer on the eastern horizon at sunrise in Chicago. Dark enough, in fact, to filter the 2004 transit of Venus and enable seeing it with the unaided eye for a few minutes while the Sun was rising!

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Temperature inversions happen everywhere, but they're prone in valleys because the air has no where to go. Cold air is dense. So it drains from high elevation regions to lower ones and hugs as close to the ground as can. This makes valleys especially vulnerable to inversions ... These inversions occur when cold air gets trapped in the valley and a layer of warm air seals it from above; which makes storms in valleys particularly worrysome

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