Abstract:
A special study of cusps and distortions in Fl-layers traces has been made from ionograms obtained at Kodaikanal during a period of about half a solar cycle. Two differnet types of disturbance have been noticed. The first one is a stationary type occuring near the low frequency end of the Fl-layer trace. It is suggested that these ridges found in the course of a disturbance are connected with the E2-layer. In the second type, the cusp appears to move along the virtual height curve and these are ascribed to travelling wave-type disturbance. It is also found that these disturbances are associated with the disappearence. It is also found that these disturbances are associated with the disappearance of equatorial E/subs/ on magnetically disturbed days. An explanation of the phenomenon is attempted in terms of internal gravity waves proposed by Hines (1960)
