Nimbostratus clouds are thick, gray clouds that cover the sky and bring continuous, steady precipitation. They typically form at low altitudes and can extend over large areas, creating a uniform cloud layer. These clouds are often associated with overcast conditions and can produce rain, snow, or drizzle. Unlike cumulonimbus clouds, which are tall and associated with thunderstorms, nimbostratus clouds are more stable and do not produce severe weather. They are important for providing moisture to the atmosphere and can last for several hours or even days, contributing to prolonged periods of wet weather.