ceilometer

Ceilometer is an instrument used to measure cloud ceiling height in meteorology. It typically uses a lidar-based or optical system that emits a light pulse upward and detects backscattered light. The time of flight is converted to distance, yielding the height of the lowest cloud layer. Modern ceilometers can operate continuously or on schedules and may report cloud-base height, layer thickness, and visibility estimates. They come in single-beam and multi-beam variants and use infrared or near-visible wavelengths to suit conditions.

Ceilometers are installed at weather stations, airports, and research sites. Data quality depends on atmospheric conditions, calibration, and safety limits for laser devices. Data are timestamped and can be integrated with other meteorological observations for weather forecasting, aviation operations, and climate studies.

In computing, Ceilometer is a separate OpenStack telemetry service that collects measurements of cloud resource usage and performance. It aggregates data from compute, storage, and network services, enabling monitoring, accounting, and policy-based automation. The project provides polling and event-driven data collection and can feed back into dashboards and alarms; in many deployments the data storage backend has evolved toward scalable time-series stores such as Gnocchi.