Photographic Study of Lightning

Photographs of lightning taken with rotating film cameras near Albuquerque, New Mexico, in the summer of 1935 show three different types of electrical breakdown. In the first type the first flash starts at the cloud, proceeds about 1 km and stops abruptly in air. This was followed in 0.008 sec. by a second flash traversing the same path but extending it about 0.22 km. The third similar flash 0.01 sec. later extended the path 0.5 km. The fourth flash extended the path clear to earth 0.0098 sec. later. The second type showed the well-known ``leader'' type of breakdown of Schonland and others. The third type of breakdown consisted of only the main violent discharge between cloud and earth. The results are briefly discussed and a new possible mechanism for lightning breakdown pointed out.