A large number of heat rays, discharged from the fireball which appeared from the explosion, wrapped the surface of the earth with abnormally high temperatures in as little as 3 seconds from the explosion.
The temperature of the earth’s surface was estimated to reach 3,000 degrees to 4,000 degrees centigrade at the hypocenter, 1,800 degrees at a distance of 1 kilometer, and more than 600 degrees in the vicinity of 1.5 kilometers away from the hypocenter. The heat caused a large-scale fire and affected even places about 4 kilometers away from the hypocenter. People outside the structures and air-raid shelters suffered severe burns.
In this section, the roof tiles exposed to the atomic bomb radiation are exhibited in order of the distance from the hypocenter. The surfaces exposed directly to the heat rays boiled and bubbled with a trace of specific foaming. The shorter the distance, the larger the bubbles became. They show the unimaginable devastation of the heat rays.
As a result of a test, it is said that the same phenomenon appeared on tiles when they were exposed to the high temperature of 1,800 degrees centigrade for four seconds.
