Clouds are the root signs of the air. When you can recognize and understand their significances the pilot can negotiate each flight with confidence. Although clouds are among the most spectacular features of our weather, they are rarely welcomed by aircrew. Clouds obscure surface features and aircraft and also envelope high ground and may be associated with severe turbulence and rain. The main difficulties are associated with thick clouds with very low base and particularly affect aircraft attempting to take-off or land. An experienced observer can sometimes judge from the appearance of clouds that a region of bad weather is moving faster or slower than originally expected, or some special hazard is developing.

Definition of Cloud

a. Cirrus Detached clouds of delicate and fibrous appearance, without shading, generally white in color and often of silky appearance.

b. Cirrostratus A thin whitish veil which dies not blurs the outline of the sun or moon. This type of cloud often gives rise to halves.

c. Cirrocumulus A corridor layer or patch composed of small white flacks, or very small globular masses without shadows and arranged in groups or lines, but more often in ripples like

d. Altocumulus A layer, or patches composed of lamina or rather flattened globular masses, the smallest elements of the regularly arranged layer being fairly small and thin, with or without shading. The elements may be arranged in groups. The clouds often resembles Cirrocumulus but on a larger scale.

e. Altostratus Striated or fibrous veil, more or less gray or bluish in color. The sun or moon shine through the cloud vaguely, as through ground glass, and may eventually be completely obscured by the cloud. Altostratus is like thick Cirrostratus but does not produce a halo.

f. Nimbostratus A low, amorphous, and rainy layer of dark gray cloud and nearly uniform appearance.

g. Stratus A uniform but usually shallow layer of cloud resembling fog but with its base above the general level.

h. Stratocumulus A layer or patches composed of globular masses or rolls. The smallest of the regularly arranged elements are fairly large, they are soft and gray with darker parts. The cloudlets are often arranged in groups, lines or waves, aligned in one or two directions and the rolls may be as close that their edges join.

i. Cumulus Thick cloud with vertical development, the upper surface is dome-shape while the base is nearly horizontal.

j. Cumulonimbus Thick cloud with develop the thunderstorm, lightning, strong wind and rain which is hazardous to aircraft flying.