calvus (cal)

One of the two species that the cloud genus Cumulonimbus (Cb) can present - the other being capillatus (cap). It is characterized by an apparently smooth, white-colored outline, without prominent protuberances or a cirriform cloud "hair," in the upper part of the aforementioned cloud. That Latin word means bald, stripped, or bare. Calvus cumulonimbi do not usually reach the tropopause, in which case the strong prevailing winds from that atmospheric level onward deform the cloud top and it takes on the characteristic anvil shape (Cb incus).