Stratus cloud classified as pannus clouds. Stratus only has one mutatus mother cloud. Stratus stratocumulomutatus clouds occur when stratocumulus opacus patches fuse to create a stratiform layer. Stratus clouds don't produce accessory clouds, but a supplementary feature praecipitatio is derived from Latin, which means "precipitation". Stratus clouds are too low to produce virga, or rain shears that evaporate before reaching the ground. A stratus cloud can form from stratocumulus spreading out under an inversion, indicating a continuation of prolonged cloudy weather with drizzle for several hours and then an improvement as it breaks into stratocumulus. Stratus clouds can persist for days in
Cumulus congestus cloud as altostratus or altocumulus which usually stop any cumulus from reaching the congestus stage by reducing the Sun's heat or acting as a layer of stable air through which the cumulus cannot rise through. Occasionally, however, particularly if the air below the mid level cloud is very warm or unstable, some of the cumuli may become congestus and the tops of them may rise above the mid level cloud layer, sometimes resulting in showers ahead of the main rainband. This is often a sign the approaching front contains at least a few cumulonimbi amongst the nimbostratus rain clouds and therefore