Description Cirrus and differences with similar clouds | Previous Top Next

Cirrus
Detached clouds in the form of white, delicate filaments or white or mostly white patches or narrow bands. These clouds have a fibrous (hair-like) appearance, or a silky sheen, or both.
Main differences between Cirrus and similar clouds of other genera
(a) Cirrocumulus
Cirrus in rounded tufts or in the form of small rounded turrets or battlements rising from a common base may be confused with Cirrocumulus presenting a similar appearance. The distinguishing criterion is that the Cirrus tufts or turrets, in contrast with those of Cirrocumulus, have an apparent width exceeding one degree when observed at an angle of more than 30 degrees above the horizon.
(b) Cirrostratus
Cirrus clouds are distinguished from Cirrostratus by their discontinuous structure or, if they are in patches or bands, by their small horizontal extent or the narrowness of their continuous parts. Cirrus near the horizon may be difficult to distinguish from Cirrostratus, owing to the effect of perspective.
(c) Altocumulus
Cirrus in rounded tufts or in the form of small rounded turrets or battlements rising from a common base is distinguished from Altocumulus presenting a similar appearance by the fact that its texture is more silky or fibrous than that of Altocumulus.
(d) Altostratus
Thick Cirrus patches are distinguished from Altostratus patches by their smaller horizontal extent and their mostly white appearance.