What defines a ceiling in meteorological terms?

In meteorological terms, a ceiling is defined as the height of the lowest layer of clouds that is either broken or overcast, or the height of the lowest layer of clouds that is considered significant and affects aviation. This definition means that the ceiling represents the lowest non-surface-based layer in the atmosphere that can impact visibility and flight operations.

Understanding this definition helps pilots and meteorologists assess conditions for flight safety, as the ceiling can indicate how much of the sky is obscured by clouds and can influence decisions about takeoff, landing, and flight routing.

The other definitions can cause confusion. The lowest cloud base of any clouds would not account for the operational impact of the clouds' coverage, while the highest cloud base in the area does not typically apply to aviation concerns. The height of the last visible cloud may imply conditions that are less relevant to understanding vertical visibility and operational impacts in flight, as it focuses on the last observable layer rather than the significant cloud layer defining the ceiling.