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Above the Alamogordo test site towered what was to become the most feared and potent symbol of
the atomic age, a mushroom-shaped cloud. After the explosion, the still-expanding ball of lighter
gases and dust, superheated beyond any fire that occurs naturally, erupted into the thin upper
atmosphere about five miles above the earth; instantly the ball of gas was surrounded by a violet glow
as heat and radiation ionized the air, creating a more vivid version of the aurora sometimes seen in the
higher latitudes where changed particles from the earth's magnetic belts are drawn down to react with
the atmosphere. Carried by the winds of the upper atmosphere, the glowing ionized air above the New
Mexican desert traveled around the world creating, as did all later atomic explosions, atmospheric
glows and odd, prolonged sunsets that faded within a few days as the air cooled and reverted to a
more stable form.
Scientists in 1945 noted a substantial difference between the atomic cloud and the relatively familiar
signs of atmospheric dust caused by volcanic explosions like that of Krakatoa in 1883. Funneled
upward by the narrow venturi of the volcanic crater, such debris rises far higher than the relatively
thin gaseous atomic cloud which is quickly dissipated by the first high-altitude winds. Dust from
Krakatoa rose into the belt of fast jet streams that lie between 12 and 20 miles up - winds still known
as "Krakatoa winds." Spread around the world by these high-speed air currents, volcanic dust forms a
belt as much as three miles deep in the upper air. As the sun sets, light striking the underside of the
cloud creates the crimson sunsets familiar from Krakatoa and such recent eruptions as that of Fuego
volcano in Guatemala in 1975. Most brilliant about thirty minutes after the sun has sunk below the
horizon, the volcanic sunset may persist for as long as a year, until the airborne dust gradually sinks to
earth.
Part of the United States's justification for the attack on Hiroshima had been that the city held the
headquarters of the 5th Division of the Japanese Army. Radio reports named Hiroshima as a "military
center" on the basis of its presence there, and the castle in which the division was billeted became the
official aiming point for the 6-29 bombardier. Later, Air Force men remarked that the bomb had been
dropped almost exactly on target. The whole unit was at calisthenics in the open air when the bomb
fell; every member died instantly.
American physicist Philip Morrison, one of the observers sent into the city thirty-one days after the
blast, was astonished at the relative lack of damage to the castle area, which must have been almost
directly under the fireball.
"Morrison passed the wreckage of the castle which had been the Fifth Division's headquarters,"
records Daniel Lang in From Hiroshima to the Moon. "The four thousand soldiers there had been
killed. Morrison's guide lamented the destruction of the castle, part of which had been used as a
military museum, where some souvenirs of an ancient victory had been preserved. The loss of these
treasures distressed the guide. So did the fact that a tree planted by Hirohito's father had been burned
black and leafless. Some water lilies in the moat of the castle had turned black, too, the guide added,
but he was happy to say that they had begun to grow again. 'I wanted to make sure of that,' Morrison
said, 'and I asked him to show me the lilies. They were growing all right.'"
The fact that the lilies were still growing proved to Morrison that, because the blast had been an air
burst, the area had not been as completely saturated in gamma radiation as Alamogordo had been,
where all life had been obliterated. The growth of the Hiroshima lilies was found to be characteristic
of the accelerated plant growth which often followed atomic explosions. Not only did the black,
leafless yet upright trees around the Hiroshima Castle at ground zero resemble the zone of burned,
standing trees on the Tunguska site but a similar acceleration of growth was discovered in plants and
trees closest to the center of the destroyed region in Siberia.
Just as the Japanese survivors first saw a "blinding flash" or "sheet of sun" in the sky, the Siberian
witnesses recalled that the 1908 fire which suddenly appeared over the Tunguska was "brighter than
the sun." The eyewitness descriptions of the Siberian explosion, in fact, coincide remarkably well with
those of Hiroshima survivors. According to one account of the morning, "a huge flame shot up that
cut the sky in two." Others spoke of an enormous "tongue of flame" or "pillar of fire" that flared over
the taiga, followed by a tall, billowing column of "black smoke" - images that fit a nuclear fireball and
mushroom cloud.
As at Hiroshima, the brilliant flash in the sky was accompanied by terrible heat. Sitting on his porch in
Vanavara, 40 miles from the explosion, S.B. Semenov saw a "huge fireball" that gave off such a fierce
heat that he could hardly remain seated. P.P. Kosolapov, a neighbor who was working at the side of
the house, felt that his ears were scorched. The heat "seized" Semenov, nearly burning the shirt off his
back. Then it grew dark, and he was thrown to the ground by the concussion. The shock wave, which
immediately followed the flash and heat, "shook the whole house," damaging the ceiling and breaking
windows. After the shock came the loud roar of the blast, like distant thunder.
In April of 1927 the Tungus Ilya Potapovich had informed Kulik that the "center of the firestorm" of
the blast occurred at the pasture land of his relative Vasily Ilich, who had a herd of fifteen hundred
reindeer. "In the same area he owned a number of storehouses where he kept clothes, household
goods, reindeer harnesses," Kulik was told. "The fire came by and destroyed the forest, the reindeer,
and the storehouses. Afterward, when the Tungus went in search of the herd, they found only charred
reindeer carcasses. Nothing remained of the storehouses; everything had burned up and melted -
clothes, utensils, reindeer harnesses, dishes, and samovars. Only a few pails remained."
No later investigator, not even those most completely committed to the meteorite theory, ever
discredited these eyewitness reports. Krinov was initially perplexed by Semenov's description of the
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