Video of combined effects
Chronological development of an air burst
The Story of Hiroshima
Since communications between the Hiroshima and higher military and naval headquarters had been severed, initial news that something frightful had occurred at Hiroshima came into Tokyo from nearby towns. People reported to the navy’s underground headquarters in Tokyo a “sinister cloud,” an “enormous explosion,” a “terrible flash,” a Reports were vague and created more puzzlement than alarm. Finally, from descriptions of the city’s destruction, Japanese military began to realize that what happened may have been the result of an atomic bomb “heavy roar.”
On the ground moments before the blast it was a calm and sunny Monday morning. An air raid alert from earlier that morning had been called off after only a solitary aircraft was seen (the weather plane), and by 8:15 the city was alive with activity — soldiers doing their morning calisthenics, commuters on foot or on bicycles, groups of women and children working outside to clear firebreaks. Those closest to the explosion died instantly, their bodies turned to black char. Nearby birds burst into flames in mid-air, and dry, combustible materials such as paper instantly ignited as far away as 6,400 feet from ground zero. The white light acted as a giant flashbulb, burning the dark patterns of clothing onto skin (right) and the shadows of bodies onto walls. Survivors outdoors close to the blast generally describe a literally blinding light combined with a sudden and overwhelming wave of heat. (The effects of radiation are usually not immediately apparent.) The blast wave followed almost instantly for those close-in, often knocking them from their feet. Those that were indoors were usually spared the flash burns, but flying glass from broken windows filled most rooms, and all but the very strongest structures collapsed. One boy was blown through the windows of his house and across the street as the house collapsed behind him. Within minutes 9 out of 10 people half a mile or less from ground zero were dead.
People farther from the point of detonation experienced first the flash and heat, followed seconds later by a deafening boom and the blast wave. Nearly every structure within one mile of ground zero was destroyed, and almost every building within three miles was damaged. [Hiroshima]
After finishing his shift at the factory, Akio Sakita returned home and went to his backyard to do the washing. He heard the drone of airplanes above, but since the air raid alarm had been called off, he assumed that the planes he saw were Japanese planes out on surveillance runs. At that moment, he heard a loud roar in the sky, and as he looked up, “wondering if it had in fact been the enemy, a blinding flash of light filled the sky and my body was showered in a wave of intense heat. I felt a searing pain in my face and threw myself on to the ground with my eyes firmly shut. The rush of heat continued for several seconds. It was like a glimpse into the horror of hell. . . . I had suffered terrible burns all over the upper half of my body. [Hiroshima]
Mr. Sumiteru Taniguchi was a sixteen year old postal carrier at the time of the bomb. He was delivering mail on his normal route in Sumiyoshi town when the atomic bomb exploded. “After the sky flashed as lightning I was thrown with a bicycle on the ground when I came to around my skin on the left arm peeled off and hung down to fingertip, my back and hips were burned and became sore and clothes nearly didn’t remain. [Nagasaki]
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 Enola Gay 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. [Hiroshima]
Trinity Test – Explosion
At 05:29:45 local time (Mountain War Time), (11:29:45 GMT) the device exploded with an energy equivalent to around 20 kilotons of TNT (87.5 TJ). It left a crater of radioactive glass in the desert 10 feet (3 meters) deep and 1,100 ft (330 meters) wide. At the time of detonation, the surrounding mountains were illuminated brighter than daytime for one to two seconds, and the heat was reported as being as hot as an oven at the base camp. The observed colors of the illumination ranged from purple to green and eventually to white. The roar of the shock wave took 40 seconds to reach the observers. The shock wave was felt over 100 miles (160 km) away, and the mushroom cloud reached 7.5 miles (12 km) in height. [..]
In the official report on the test, General Farrell wrote, “The lighting effects beggared description. The whole country was lighted by a searing light with the intensity many times that of the midday sun. It was golden, purple, violet, gray, and blue. It lighted every peak, crevasse and ridge of the nearby mountain range with a clarity and beauty that cannot be described but must be seen to be imagined…”
News reports quoted a forest ranger 150 miles (240 km) west of the site as saying he saw “a flash of fire followed by an explosion and black smoke.” A New Mexican 150 miles (240 km) north said, “The explosion lighted up the sky like the sun.” Other reports remarked that windows were rattled and the sound of the explosion could be heard up to 200 miles (320 km) away.
Interview with Patricia Ondrovic
KT: What did you do when the South Tower started coming down?
PO: I didn’t know what was happening, but there was a loud “roar” — lots of crashing sounds. I was attempting to put my stretcher back into the vehicle. The ground was shaking and I saw a sea of people, mostly the various agencies on scene, Fire, Police, EMS, all running towards me. I had no idea what they were running from, but I decided I’d be ahead of them and just started running west towards the river. As I was running, parked cars were blowing up and some were on fire, the street was cracking a bit as well. Very shortly after I started running, everything became one big black cloud. I was near the West Side Highway and I couldn’t see around me anymore.
Ondrovic Interview – Buildings WTC 5 and 6 blowing up at the same time as WTC 2 (South Tower)
KT: Can you describe more about how the building blew up on you? Did you feel the shock wave from the explosion and/or debris falling down near you?
PO: Well, one second I was trying to put my stretcher into the ambulance, the next thing I know I am thrown to the ground as the ground was shaking. Debris was flying at me from where the building I was parked in front of. There was a continual loud rumbling, there was just debris flying from every direction and then everything being covered in the black and gray smoke.
KT: Let’s recap real quickly; your ambulance was parked backed up against the WTC 6, near the 6’s corner by the alleyway between the WTC 5 and 6 …
WRH – Comment
“We start walking back there and then I heard a ground level explosion and I’m like holy shit, and then you heard that twisting metal wreckage again.” [James McKinley — E.M.T. (E.M.S.)]
When the rescue team reached an area directly in front of Tower Two, Antonio said he’d take over the equipment cart Will had pushed from Building 5. … The team moved ahead. … Suddenly the hallway began to shudder as a terrible deafening roar swept over them. That’s when Will saw the giant fireball explode in the street. [bowhunter.com]
WRH video – fireball
His story: He escapes from the South Tower and while he is running away, he is hit by a fireball. He is probably the last person out alive. He says he saw a fireball and heard a loud noise, and that’s all he remembers. He woke up 6 days later in St Vincents.
‘As Ron DiFrancesco ran away [from WTC 2] he was hit by a fireball … he was probably the last person out alive. “I saw the fireball and heard a loud noise. That’s all I remember…”‘
“A giant rolling ball of flame”
“All of a sudden I heard a roar and I saw one of the towers blow … I saw from street level as though it exploded up, a giant rolling ball of flame…
I hear simultaneously this roar and see what appears to be a gigantic fireball rising up at ground level . . . I remember seeing this giant ball of fire come out of the earth as I heard this roar” [Running Toward Danger: Stories Behind the Breaking News of 9/11 – P 239]
“It was hot – very, very hot”
Survivor in WTC 1 stairwell during WTC 2 collapse: “…and all of a sudden this huge cloud of dark grey smoke comes shooting up the stairway … and it was hot – very, very hot.”
White smoke emerging from the dust cloud of the collapsing WTC 2
“Glass like blew out and threw me onto the sidewalk”
“I was standing next to 1 World Trade Center and then all of a sudden I heard rumbling and we all started running away from it. The glass like blew out and threw me onto the sidewalk … and I couldn’t see for like twenty seconds…”
White smoke at the base of WTC 1 seconds before its collapse
Video with zoom:
Video without zoom:
Smoke rising from the World Trade Center wreckage
The smoke rising from the wreckage should have been black, not white.
The Mach Stem
If the explosion occurs above the ground, when the expanding blast wave strikes the surface of the earth, it is reflected off the ground to form a second shock wave traveling behind the first. This reflected wave travels faster than the first, or incident, shock wave since it is traveling through air already moving at high speed due to the passage of the incident wave. The reflected blast wave merges with the incident shock wave to form a single wave, known as the Mach Stem. The overpressure at the front of the Mach wave is generally about twice as great as that at the direct blast wave front.
At first the height of the Mach Stem wave is small, but as the wave front continues to move outward, the height increases steadily. At the same time, however, the overpressure, like that in the incident wave, decreases because of the continuous loss of energy and the ever-increasing area of the advancing front. After about 40 seconds, when the Mach front from a 1-megaton nuclear weapon is 10 miles from ground zero, the overpressure will have decreased to roughly 1 psi.
Some Hiroshima and Nagasaki videos
From: Trinity Atomic Web Site
Hiroshima videos – URL: http://www.cddc.vt.edu/host/atomic/hiroshim/hirovid1.html
Nagasaki videos – URL: http://www.cddc.vt.edu/host/atomic/hiroshim/ngvid1.html
Note: These videos are taken from the film The Atom Strikes, by the U.S. Army Signal Corps. This film is of historic interest and does not necessarily represent the policy or plans of the creating agency.
1. Views from Ground Zero
This video clip shows views in various directions away from ground zero at Hiroshima.
2. Japanese Military Headquarters
The Japanese Military Headquarters were 0.3 mi from ground zero at Hiroshima. It was a closely guarded secret for many, many years that a number of American POW’s were held here when the bomb was dropped.
3. Shadows on a Bridge
At 0.6 mi from ground zero, the intense heat etched any surface facing the fireball.
1. Nagasaki Fireball
This video clip shows Nagasaki fireball and early mushroom cloud as seen from an observation plane.
2. Nagasaki Mushroom Cloud
This video clip shows the later Nagasaki mushroom cloud as seen from an observation plane.
3. Aerial Overview of Nagasaki
An aerial survey of Nagasaki after the atomic blast.
Effects of Nuclear Weapons video
Image from video
VIDEO: EFFECTS OF NUCLEAR WEAPONS
Hiroshima and Nagasaki pictures
http://www.history.com/images/media/slideshow/hiroshima-and-nagasaki/bomb-exploding-nagasaki.jpg URL: http://www.history.com/photos/hiroshima-and-nagasaki/photo2 Caption: Atomic Bomb Exploding in Nagasaki: A mushroom cloud from an atomic bomb rises over Nagasaki. The second atomic bomb was dropped on the city of Nagasaki in August, 1945, in the last days of WWII shortly before the surrender of Japan. (Photo Credit: Corbis)
http://www.history.com/images/media/slideshow/hiroshima-and-nagasaki/fat-man-atomic-bomb-replica.jpg URL: http://www.history.com/photos/hiroshima-and-nagasaki/photo2 Caption: Replica of Fat Man Atomic Bomb: A replica of the atomic bomb dropped on Nagasaki, a plutonium-implosion bomb nick-named “Fat Man”. (Photo Credit: Corbis)
http://www.history.com/images/media/slideshow/hiroshima-and-nagasaki/hiroshima-aftermath.jpg URL: http://www.history.com/photos/hiroshima-and-nagasaki/photo2 Caption: Hiroshima Aftermath: March, 1946. Eight months after the atomic bomb was dropped Hiroshima still stands in ruins. (Photo Credit: Corbis)
http://www.history.com/images/media/slideshow/hiroshima-and-nagasaki/man-walks-through-bombed-nagasaki.jpg URL: http://www.history.com/photos/hiroshima-and-nagasaki/photo2 Caption: Man Walks Through Nagasaki: A Japanese man walks through the damaged lands of Nagasaki two months after the atomic bomb was dropped over the city. (Photo Credit: Corbis)
URL: http://www.history.com/photos/hiroshima-and-nagasaki/photo2 Caption: Japanese Soldiers in Nagasaki After the Bombing: October 5, 1945. Japanese soldiers survey the damage in Nagasaki, two months after the atomic bomb was dropped over the city. (Photo Credit: Corbis)
http://www.history.com/images/media/slideshow/hiroshima-and-nagasaki/nagasaki-after-atomic-bomb.jpg URL: http://www.history.com/photos/hiroshima-and-nagasaki/photo2 Caption: Damaged School in Nagasaki: August 13, 1945. The remains of a former elementary school and a dead tree stand in the rubble of Nagasaki a week after the atomic bomb was dropped on the city. (Photo Credit: Corbis)
http://www.history.com/images/media/slideshow/hiroshima-and-nagasaki/nagasaki-rubble.jpg URL: http://www.history.com/photos/hiroshima-and-nagasaki/photo2 Caption: Rubble In Nagasaki After Atomic Bomb Explosion: October 5, 1945. Rubble and dead trees are still the dominant features of the Nagasaki landscape two months after the atomic bomb was dropped on the city. (Photo Credit: Corbis)
http://www.history.com/images/media/slideshow/hiroshima-and-nagasaki/nagasaki-buildings-after-bomb.jpg URL: http://www.history.com/photos/hiroshima-and-nagasaki/photo2 Caption: Nagasaki Medical College After Atomic Bombing: Only the reinforced concrete buildings of the Nagasaki Medical College hospital remain standing after the United States dropped its second atomic bomb on August 9, 1945. The hospital was located 800 meters from ground zero of the atomic bomb explosion. (Photo Credit: Corbis)
http://www.history.com/images/media/slideshow/hiroshima-and-nagasaki/hiroshima-after-bomb.jpg URL: http://www.history.com/photos/hiroshima-and-nagasaki/photo2 Caption: Chamber of Industry and Commerce Building Standing in Destroyed Hiroshima: The Hiroshima Chamber of Industry and Commerce was the only building remotely close to standing near the center of the atomic bomb blast of August 6, 1945. It was left unrepaired as a reminder of the event. (Photo Credit: Corbis)
http://www.history.com/images/media/slideshow/hiroshima-and-nagasaki/hiroshima-memorial.jpg URL: http://www.history.com/photos/hiroshima-and-nagasaki/photo2 Caption: Modern Day Hiroshima Memorial: Hiroshima Memorial Park seen with modern-day Hiroshima visible in the background. (Photo Credit: Corbis)