Knowing the exact height of the cloud base is essential for pilots during takeoff and landing. A ceilometer works on the principle of LIDAR or optical reflection; it sends a vertical beam of light into the sky and detects the backscattered signal from cloud droplets. By calculating the time delay between the transmission and the return of the signal, the device determines the cloud’s altitude. Modern ceilometers can detect multiple layers of clouds simultaneously. This information helps meteorologists categorize cloud types and assess the stability of the lower atmosphere, providing vital data for both local weather reports and flight safety.