A stratus cloud is a low, flat, gray layer that can spread across most or all of the sky. Its name comes from the Latin word stratus, meaning “layer” or “spread out,” describing its uniform, sheetlike appearance.
Stratus clouds form when stable air is lifted gently or when fog rises slightly above the ground. Unlike towering cumulus clouds, they have little vertical development and usually look smooth and featureless. They may produce mist, drizzle, freezing drizzle, snow, or snow grains, but generally do not bring heavy showers or thunderstorms.
Stratus is often confused with nimbostratus because both can look gray and cover the sky. The key difference is precipitation: nimbostratus is a thicker, rain- or snow-producing cloud associated with prolonged precipitation. Cirrus clouds are high, thin, and wispy, while cumulus clouds are puffy and associated with stronger vertical air movement.