Nimbostratus clouds are low and middle level clouds. They are dark gray with precipitation falling from them. The cloud bases are diffuse and difficult to determine because of falling precipitation. Low Clouds Cumulus clouds are low. They appear puffy, and look like cotton balls, popcorn, or cauliflower.
Stratus clouds are low.
They are light or dark gray and generally uniform in appearance. They cover most of the sky. Stratocumulus clouds are low, with irregular masses. They are rolling or puffy in appearance, sometimes with space between the clouds. Cumulonimbus clouds are large clouds with dark bases and tall, billowing towers.