Abstract
Since the reflection of electromagnetic waves from the lower atmosphere, including troposphere, has been first reported by Friend and Colwell of America in 1937, experiments were developed also in England and in Japan. This low reflecting layer is called C-layer and its height is estimated to range from about 30km to 1km.
Recently, advanced experiments have been carried out in America, and followings can be predicted as the correlations between C-layer reflections and meteorological conditions.
(1) When the cold front passes throgh the station observing C-layer, waves are reflected from the lower level, which can be attributed to the plane of discontinuity.
(2) Waves are reflected from the point, where temperature inversion or marked variation of humidity takes place.
(3) Scattered echos are reflected from gusty air.
(4) Some correlations exist between C-layer reflections and thunder clouds.
Echo patterns and continuous height records, obtained in Japan, are shown in figures 1 and 2.
It is pointed out that explanation of the mechanism of reflection from C-layer is of future importance from the viewpoint of wave propagation and meteorology. It is hoped that the study of the lower atmosphere is promoted by the intimate cooperation of radio sonde, radio sounding technique and the knowledge of meteorology.
