When warm, moist air is mixed with drier, cooler air and the mixture is moving beneath warmer, lighter air above, clouds will often form as rolls or waves. Sometimes, especially in summer, there are gaps through which the Sun can shine. This cloud is called stratocumulus, meaning sheets of lumpy cloud. Stratocumulus is grey, white, or a mixture of both, usually with some darker patches. It is a low-level cloud that can look threatening, but unless it is very thick usually only drizzle or light precipitation fall from it. It can also form in air forced to rise over hills. Its base is typically at 1,000-7,000 ft (300-2,000 m). Although stratocumulus is not usually a badweather cloud, its presence may indicate that worse weather is on its way, or is just clearing.

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