What is a ceiling, as the term is used in aviation weather reports?

In aviation weather a ceiling has a precise meaning: the height above ground of the lowest layer reported as broken or overcast, or the vertical visibility into an obscuration such as fog or heavy smoke. Coverage is the key, because it is reported in eighths of the sky — few and scattered layers are not ceilings, while broken and overcast are. The distinction matters to a remote pilot in two directions. First, the ceiling determines usable altitude, since the aircraft must stay 500 feet below any cloud, so a 700-foot ceiling leaves 200 feet. Second, and more easily missed, the cloud clearance requirement applies to any cloud, so a scattered layer below the reported ceiling constrains the operation even though it is not a ceiling by definition. Vertical visibility is the case worth remembering separately: in fog the sky is not visible at all, so the report gives how far up one can see rather than a layer height.

A ceiling is the height above ground of the lowest broken or overcast layer, or the vertical visibility into an obscuration where the sky is not discernible.

A ceiling is the height above ground level of the lowest broken or overcast layer, or the vertical visibility into an obscuration. Few and scattered layers are not ceilings, though cloud clearance requirements apply to any cloud.

Broken or Overcast, Lowest One. Few and scattered do not count as ceiling — but they still count for clearance.

Vertical visibility appears as VV followed by a height, and it means the sky is obscured rather than that a layer exists at that height.

• •Counting scattered layers as a ceiling
• •Planning altitude from the ceiling while ignoring a lower scattered layer
• •Confusing a weather ceiling with an aircraft's service ceiling