The operation, in a high flying airplane, of a simple 16 mm time lapse motion picture camera produces an excellent record of the cloud systems and other visual atmospheric patterns existing over large areas of continent and ocean.

Over the past several years such records were obtained from both jet and propeller driven planes through the cooperation of the Boeing Airplane Company and the Air Weather Service, U.S.A.F. with the Munitalp Foundation.

For best results it was found that the camera should be mounted at right angles or at 45 degrees with respect to the flight path and with a downward tilt of from five to twenty degrees depending on the cruising height of the plane. A two second interval was found to be suitable for good results with planes with an average speed in the range of 300–600 mph. Intervals of four to even ten seconds are permissible at these speeds for economy or convenience. When such a sequence is viewed as a movie, near clouds move by at a different rate from those in the middle or far distance thus giving an excellent illusion of three dimensions. Successive frames may be selected from a sequence and viewed in a stereoscope to get a three dimensional view of the area photographed. When projcted at sound speed in a movie projector, a film made with a two second interval sequence presents the illusion that the viewer is travelling through the sky at a speed of nearly 29,000 mph.

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Footnotes

* Present affiliation: USAF Hurricane Liaison Office, U. S. Weather Bureau, Miami, Florida.