Descriptive of a sky cover of from 0. 6 to 0. 9 (to the nearest tenth). This is applied only when obscuring phenomena aloft are present, that is, not when the sky cover is composed entirely of surface-based obscuring phenomena. In aviation weather observations, a broken sky cover may be explicitly identified as thin (predominantly transparent); otherwise a predominantly opaque status is implicit. An opaque broken sky cover is the minimum requirement for a ceiling, and this is frequently termed broken ceiling.