THE 29.5-DAY VARIATIONS OF THUNDERSTORM ACTIVITY

V. A. Mullayarov, R. R. Karimov, and V. I. Kozlov

The superposed epoch method is used to consider 29.5-day variations of VLF noises of thunderstorm origin at the frequency of 8.7 kHz, as observed at the station of Yakutsk in 1979—1994. In the winter nighttime, the VLF noises reflect activity of the African World Thunderstorm Center, while in the summer daytime, they are evidence of local thunderstorms in the east of Siberia. As a zero day, that of new moon is chosen. It is found that significant increase in thunderstorm activity in the African World Center occurs on the 6th day after the key day, while in the east of Siberia, on the zero day.