In meteorology, an inversion is a deviation from the normal change of an atmospheric property with altitude. It almost always refers to an inversion, i. e. an increase in temperature with height. An inversion can lead to such as smog being trapped close to the ground. An inversion can also suppress convection by acting as a cap, if this cap is broken for any of several reasons, convection of any moisture present can then erupt into violent thunderstorms. Temperature inversion can notoriously result in freezing rain in cold climates. g, given the right conditions, the normal vertical temperature gradient is inverted such that the air is colder near the surface of the Earth. This can occur when, for example, a warmer, less-dense air mass moves over a cooler, denser air mass. This type of inversion occurs in the vicinity of warm fronts, with sufficient humidity in the cooler layer, fog is typically present below the inversion cap. This effect is virtually confined to regions as the ocean retains heat far longer. In the polar regions during winter, inversions are nearly always present over land, a warmer air mass moving over a cooler one can shut off any convection which may be present in the cooler air mass. This is known as a capping inversion, such capping inversions typically precede the development of tornadoes in the Midwestern United States. In this instance, the layer is actually quite warm. An inversion can develop aloft as a result of air gradually sinking over an area and being warmed by adiabatic compression. A stable marine layer may develop over the ocean as a result. The accumulated smog and dust under the inversion quickly taints the sky reddish and this can become a problem in cities where many pollutants exist. During a severe inversion, trapped air pollutants form a haze that can cause respiratory problems. The Great Smog of 1952 in London, England, is one of the most serious examples of such an inversion and it was blamed for an estimated 11,000 to 12,000 deaths. Sometimes the inversion layer is at a high altitude that cumulus clouds can condense. This decreases the amount of sunlight reaching the ground and prevents new thermals from forming, as the clouds disperse, sunny weather replaces cloudiness in a cycle that can occur more than once a day
Smoke rising in Lochcarron, Scotland, is stopped by an overlying layer of warmer air (2006).
A temperature inversion in Budapest, Hungary viewing Margaret Island - 2013