Unusual Clouds: Mammatus
In the warm season, after passing a thunderstorm in the sky, sometimes clouds of a bizarre shape resembling a udder can be observed. In meteorology, udder-shaped clouds are called Mammatus, and they are one of the varieties of cumulus clouds that have a cellular structure.
Mammatus "fumbled" clouds are located, as a rule, under the "parent" cluster of powerful cumulus or cumulonimbus clouds. Usually the observer sees Mammatus in the form of gray clouds with darker, as if hanging down elements.
However, at low altitudes of the Sun above the horizon (for example, at sunset), Mammoths may acquire a gray-blue, gray-pink, golden and even reddish color.
Because of its ominous appearance, "udder-shaped" clouds are often considered the forerunners of an impending storm or hurricane.
Mammatuses are always associated with thunderstorm storms and, therefore, with cumulonimbus. At the same time, these clouds can be separated from the storm focus at a distance of up to several tens of kilometers. Mammatus remain in the sky from several minutes to several hours, gradually disappearing along with the fading thunderstorm.
“Udder-shaped” clouds consist, as a rule, of ice, but can also be a mixture of ice and water.
Individual “petals” of mammutuses have diameters of 1-3 km with an average length of 0.5 km. Petal exists on average 10 minutes, but a whole cluster lives from 15 minutes to several hours.
For the formation of mammutus, a neighborhood of a humid and unstable distributed air mass in the middle and upper parts of the troposphere (atmosphere layer, at temperate latitudes up to 10-12 km) above the dry air mass occupying the lower part of the troposphere is necessary.
Under such conditions, a system of small ascending and descending air currents appears against the background of the general descending air flow under falling ice crystals “anvil” of cumulonimbus clouds. These flows lead to the formation of a characteristic form of clouds.
In the USA, the appearance of Mammatus was previously associated with the appearance of a tornado in an ensemble of cumulonimbus cells, however, it is now generally accepted that the appearance of Mammatus does not mean that a tornado or tornado could appear.
However, thunderstorms causing “udder-shaped” clouds are characterized by a high probability of occurrence of ball lightning, as well as wind shear.Therefore, aircraft crews need to avoid not only cumulonimbus (Cumulonimbus) clouds, but also Mammatus.
Nevertheless, the appearance of Mammatus in the sky suggests that the most powerful and dangerous part of the storm has already passed.
Mammatus can be observed in the middle latitudes of Russia, but quite rarely. They usually arise on damped thunderstorms in the rear (downward) part of the anvil.
It is the fact that clouds are formed on the descending movements of air, makes them unique, because, as you know, clouds form during ascending currents.