Rainbow ice cap over the "Alberto"

May 30, tropical depression Alberto was located over the Illinois at this time Chris Moore took this picture of the city of Streator. As told to the author, the setting sun was covered by Cirrus clouds in the back, and colorful rainbow ring cloud enveloped the ridge on the Western edge of the storm.

It is a pileus, or "cap" on the top of a cumulonimbus cloud. It occurs when strong vertical air currents penetrate the isothermal layer. The appearance of a rounded ice "cap" is a sign that the atmosphere is dominated by strong updrafts, and the humidity is quite high. The moist air above the cloud cools and condenseries, which leads to the formation of the pileus. Since "caps" are formed very quickly, droplets of water inside them, usually of the same size, and it is a suitable condition for reflections. Uniform droplets scatter the sun's light is passing, and we can see bright pastel tones.

Usually "cap" appear on warm, summer days when the sky is decorated with towering cumulonimbus clouds. However, in this case, Alberto has created all the conditions for their appearance in late spring.

Translated by «Yandex.Translator»