Stratus refers to low-lying clouds. Stacks of layers with a uniform base characterize these clouds. This can cause the airplane captain difficulty in operating an aircraft.
Stratus clouds are generally described as featureless clouds that appear flat or hazy. They vary in color from dark grey to white, and they can produce a light drizzle or even snow. If the sun is partially obscured by a haze or a uniform coating of clouds, stratus clouds are most likely what is seen.
In other words, stratus clouds are essentially fog that appears above ground and is formed when cold air moves at low altitudes over the earth or when the morning fog lifts.
The different Stratus Variations
Some of the other stratus cloud types that an airplane captain must be aware of include:
Stratus nebulosus –appear as a good sign of atmospheric stability and appear as a featureless or nebulous cloud layer
Stratus fractus –have an irregular shape and a ragged appearance
Stratus opacus – these nebulous or milky clouds are opaque enough to block out the sun
Stratus translucidus – considered more thin and translucent than opacus clouds and allow the sun or moon to be in view
Stratus undulatus – though rare, this cloud formation occurs due to a disturbance on the gentle wind shear