Cloud Types
Table 1-6 lists some of the more common types of clouds, their characteristics, and
some of the hazards associated with each.
Type
Characteristics
Hazards to Aviation
Fibrous and delicate in appearance.
Flying conditions are good.
Clouds look like white wisps against the
Negligible turbulence. Pure
sky. First sign of approaching bad
ice crystal composition of
weather. When these clouds become
these clouds precludes
more compact and merge into
surface icing on the aircraft.
cirrostratus, it may indicate an
approaching warm front.
Appear like fleecy flakes or small white
Light to moderate
cotton balls. Like the scales on a fish,
turbulence. No icing on
and often called a mackerel sky.
aircraft surfaces.
Cirrostratus
Smooth, thin-layered cloud covering all
Icing and turbulence
or most of the sky, giving the sky a milky usually present. No hazard
appearance. Produces halo around sun to flying.
or moon. When these clouds lower,
thicken, and merge into altostratus, the
approach of a warm front and bad
weather is imminent.
Altocumulus
Sometimes appear like cirrocumulus,
Poor visibility within these
but the balls or flakes are thicker and
clouds. Light to moderate
grayer. Appear similar to a herd of
turbulence and icing. The
sheep in the sky. The underside of each
icing is usually the clear
cloud is dark because of the thickness.
type.
Altostratus
Appear as a thick gray or blue-gray
Light to moderate icing
smooth overcast. Thicker and less
(predominantly rime ice).
transparent than cirrostratus clouds.
Light turbulence. Visibility
Precipitation in the form of light rain or
within these clouds is 50 to
snow.
200 yards.
Thick, dark gray clouds that are
Moderate to heavy
formless in appearance. Precipitation is
turbulence and icing with
always falling from these clouds (may
very poor visibility within
not always reach the surface).
and below the cloud.
Stratocumulus
Occur as an extensive and fairly level
Poor visibility within these
layer marked by thick rolls and dark,
clouds. Light to moderate
rounded masses underneath.
turbulence. Moderate icing
Precipitation infrequent; when it occurs,
conditions. May form clear
it is in the form of very light rain showers
or rime ice.
1-12
