Tilts in the Ionosphere

EXPERIENCE with high-frequency radio direction finding has suggested that some of the deviations from great-circle bearings observed on signals propagated by way of the ionosphere may be attributed to a tilting or wrinkling of the reflecting layer, particularly in the case of the F -layer. A previous communication 1 has described systematic effects due to large-scale tilts occurring around sunrise. The present note concerns deviations observed at other times, which may be attributed to a more random wrinkling of the reflecting layer. These effects are distinct from those caused by smaller-scale ionospheric irregularities which give rise to the fading and comparatively rapid fluctuations of bearing of single echoes 2 . Evidence of the existence of such tilting of the layer, with some indication of the order of magnitude of the linear dimensions involved, may be of interest, and the following preliminary results of work now in progress at the Radio Research Station, Slough, are therefore given.