Abstract
A set of maps representing the topography of condensation level in space and time during the period from the 1st to the 23rd of August, 1938, has been constructed. The materials used in the maps are obtained from surface observations of 70 or more stations. It can be tentatively inferred that thundery conditions will occur if the condensation level of surface air is lower than the level 700 mm Hg. (about 600-700 m height). The set of maps, Fig. 1 and 2, represents the topography over Kyusyu District on the 20th of August at 9h and 12h. It appears reasonable to suppose that the low condensation level was actually responsible for the severe thunderstorm on that day. Fig. 4 represents the topography on the 12th of August at 12h. An examination of Fig. 4 indicates that on that day would not have occured by the ascent of surface air, the condensation below a level of about 700 mm Hg. On that day the thunderstorm actually did not originate over Kyusyu. It is, of course, impossible to draw any definite conclusions from the maps on rainy days. On rainy days, even if conditions of low condensation level appear quite favourable for a thunderstorm, any thunderstorm may not actually happen.
