Low clouds, called stratus clouds, are at altitudes up to 6,500 feet . These clouds form a solid sheet or layer of cloud mass. Stratus clouds are uniform gray in color and almost cover the entire sky. Light mist or drizzle is sometimes associated with Stratus clouds. A Stratus cloud touching the ground is fog.
Stratocumulus clouds are low, puffy and gray.
Most form in rows with blue sky visible in between. Rain rarely occurs with Stratocumulus clouds, however, they can turn into Nimbostratus. Nimbostratus clouds are dark gray with a ragged base. Rain or snow is associated with Nimbostratus clouds. Cumulonimbus are generally known as thunderstorm clouds.