What height is assigned to cloud layers with a base less than 50 feet?

The height assigned to cloud layers with a base less than 50 feet is 0 feet. This is based on the definitions used in aviation meteorology, where clouds that form at such low altitudes are considered to be at the ground level. In this context, "0 feet" signifies that the base of the cloud layer is essentially at the surface.

Clouds with bases below 50 feet often correspond to conditions such as fog where visibility is restricted, but as far as measurement is concerned, they are treated as being coincident with the ground. Assigning a height of 0 feet helps pilots understand that these clouds may have significant implications for flight, including effects on visibility and adherence to specific flight rules regarding low visibility conditions.