What is the primary purpose of a ceiling in aviation weather?

The primary purpose of a ceiling in aviation weather is to define the height of the lowest layer of clouds that covers more than half the sky, which plays a crucial role in visual flight operations. A properly established ceiling is essential for pilots, particularly those operating under Visual Flight Rules (VFR), as it informs them of the vertical visibility. When the ceiling is low, it can significantly limit a pilot's ability to see the ground or navigate effectively, potentially leading to dangerous situations.

Knowing the ceiling height helps pilots make informed decisions about flight operations, including takeoffs and landings. A higher ceiling generally allows for safer flying conditions, while a lower ceiling often necessitates adherence to Instrument Flight Rules (IFR). In summary, understanding and interpreting the ceiling in aviation weather is vital for ensuring safe navigation and operation within the airspace.