Height of base: surface to1,500 ft Colour: Usually grey. Shape: May appear as a layer with a fairly uniform base or in ragged patches, especially during rain falling from a cloud layer above. Fog will often lift into a layer of stratus due to an increase in wind or rise in temperature. As the sun heats the ground the base of stratus cloud may rise and break becoming shallow cumulus cloud as its edges take on a more distinctive form. Other features: If thin, the disc of the sun or moon will be visible (providing there are no other cloud layers above). If thick, it may produce drizzle or snow grains.