In aviation weather, how is "ceiling" defined?
Why →
Ceiling is the height AGL of the lowest layer covering more than half the sky. Specifically BKN (5–7/8) or OVC (8/8). FEW and SCT layers do NOT constitute a ceiling. The ceiling directly determines IFR vs. VFR conditions and limits the usable airspace below the 500-foot cloud clearance requirement.The trap →
FEW (1–2/8) and SCT (3–4/8) are NOT ceilings. They don't cover more than half the sky. The highest cloud layer is irrelevant to ceiling. The lowest defining layer is what matters operationally.SOURCE → FAA Meteorology / PHAK Chapter 12CHECKED APR 21ACS III.A.K1MED