The atomic cloud (mushroom cloud) produced just after the burst
is one of the most intensive characteristics of the A-bomb
explosion. The Hiroshima Meteorological Observatory reported
that just after the flash, black smoke rose from the ground up
to the sky reaching an altitude of several thousand meters, and
covered the whole city. When the fireball disappeared, the angry
clouds, like grey smoke, rose and reached an altitude of 8,000
meters in 5 minutes after the explosion. One of the EnolaGay
crew recorded in his flight diary, "9:00a.m.....Clouds were
observed. Altitude of 12,000 meters or more." From a distance
the cloud formation looked like a mushroom growing out of the
ground, with white cloud at the top and yellowish clouds
enveloping reddish-black clouds, creating a color that cannot be
described as while, black, red or yellow. In Nagasaki, from an
observation point at the air-raid lookout post on Kouyagi Island
located about 8 kilometers south of the city, just after the
flash it appeared that a huge