ceilometer

in atmospheric chemistry
https://doi.org/10.1351/goldbook.C00917
An automatic, recording instrument for reading the height of the cloud-base.
Source:
PAC, 1990, 62, 2167. 'Glossary of atmospheric chemistry terms (Recommendations 1990)' on page 2178 (https://doi.org/10.1351/pac199062112167)