Reflexions from irregularities in the ionosphere

As part of the investigation of travelling disturbances in the ionosphere during four years, a close study has been made of small daytime changes in the virtual height of F-region reflexions with periods of 10 min to 1 h. In some cases, complex reflexions are observed. It is shown that although three distinct types of complexity may be recognized, they can all be explained simply as reflexions from a curved surface of the type associated with travelling disturbances, the diversity of type resulting from differing group retardations in the different paths.