Ceiling projector
![Ceiling projector exterior](/Images/godic/202501/03/Ceiling_projector_extexterior1035.JPG")
![Interior of a ceiling projector](/Images/godic/202501/03/Ceiling_projector_interior1035.JPG")
![Alidade for use with a ceiling projector](/Images/godic/202501/03/Alidade_for_ceiling_projector1035.JPG")
The ceiling projector or cloud searchlight is used to measure the height of the base of clouds (called the ceiling) above the ground. It is used in conjunction with an alidade, usually positioned 1000 ft (304.8 m) away and wherever possible set at the same level.