A ceilometer is an optical remote-sensing instrument used to measure cloud base height and vertical visibility. It operates by emitting laser pulses into the atmosphere and analyzing the backscattered light reflected by clouds, aerosols, or precipitation. Widely deployed at airports, meteorological stations, and research sites, ceilometers provide continuous, real-time data essential for aviation safety, weather forecasting, and climate monitoring. Designed for unattended operation, modern ceilometers offer high reliability, low maintenance, and accurate performance under diverse environmental conditions.