Altostratus clouds are a type of mid-level cloud that typically form between 6,500 and 23,000 feet in the atmosphere. They appear as a gray or blue-gray layer that can cover the entire sky, often indicating that rain or snow may be on the way. These clouds are composed of water droplets and can sometimes produce light precipitation. Unlike cumulus clouds, which are fluffy and white, altostratus clouds have a more uniform appearance. They can block sunlight, creating a dim, overcast sky. When the sun shines through, it may appear as a bright spot, but the overall effect is a muted light.