Nuclear explosions create giant fireballs that generate a blinding flash and a searing heatwave. The fireball engulfs the surrounding air, getting larger as it rises like a hot air balloon. As the fireball and heated air rise, they are flattened by cooler, denser air high up in the atmosphere, creating the mushroom “cap” structure.
At the base of the cloud, the fireball causes physical destruction by sending a shockwave moving outwards at thousands of miles an hour. A strong updraft of air and dirt particles through the center of the cloud forms the “stem” of the mushroom cloud. In most atomic explosions, changing atmospheric pressure and water condensation create rings that surround the cloud, also known as Wilson clouds.
Over time, the mushroom cloud dissipates. However, it leaves behind radioactive fallout in the form of nuclear particles, debris, dust, and ash, causing lasting damage to the local environment. Because the particles are lightweight, global wind patterns often distribute them far beyond the place of detonation.
Here are the 10 largest nuclear explosions in history.
1. Tsar Bomba (50 megatons)
On October 30, 1961, the Soviet Union dropped the most powerful nuclear weapon ever exploded on the archipelago of Novaya Zemlya, north of the arctic circle. Yielding an explosion of 50 megatons the “Tsar Bomba”, as it is sometimes called, was about 3,300 times more powerful than the 15 kilotons nuclear weapon dropped on Hiroshima.
The hydrogen bomb, designated as the Soviet RDS-220, was also dubbed “Big Ivan” and “Vanya”, though “Tsar Bomba” (translated to King of Bombs) is its most popular moniker. It needed a specially designed plane because it was too heavy to carry on conventional aircraft. The bomb was attached to a giant parachute to give the plane time to fly away. The explosion obliterated an abandoned village 34 miles (55 km) away and generated a 5.0 – 5.25 magnitude earthquake in the surrounding region.
The fireball from the explosion was nearly 6 miles (9.7 km) in diameter. Tsar Bomba’s mushroom cloud breached through the stratosphere to reach a height of over 37 miles (60 km), roughly six times the flying height of commercial aircraft. Ironically, the bomb could have been much more powerful. It was designed to have an explosive yield of up to 100 megatons, but it was detonated at 50 megatons.
2. Test 219 (24.2 megatons)
On December 24, 1962, the Soviet Union dropped a rather unpleasant Christmas present over the test site on the Novaya Zemlya archipelago. The atmospheric nuclear test was carried out using an intercontinental ballistic missile (ICBM), with the bomb exploding at a height of 2.3 miles (3.8 km) above sea level, yielding a destructive radius of 25 miles (41 km).
At 24.2 megatons, this nuclear bomb was less than half as powerful as the “Tsar Bomba” bomb. It also about 1,600 times stronger than the bomb dropped on Hiroshima. Test 219 would be one of the last nuclear bombs dropped from the air by the Soviet Union, as a test ban treaty in 1963 banned aboveground testing and future tests were conducted underground.
3. Test 147 (21.1 megatons)
On August 5, 1962, the Soviet Union dropped a 21.1-megaton nuclear bomb over the Novaya Zemlya archipelago. This bomb clocks in as being about 1,400 times as powerful as the one dropped on Hiroshima.
4. Test 174 (20 megatons)
On September 27, 1962, the Soviet Union dropped a 20-megaton nuke over the Novaya Zemlya archipelago. It is about 1,330 times more powerful than the Hiroshima bomb.
5. Test 173 (19.1 megatons)
On September 25, 1962, the Soviet Union dropped a 19.1-megaton nuke over the Novaya Zemlya archipelago. It is about 1,270 times more powerful than the Hiroshima bomb.
6. Castle Bravo (15 megatons)
On March 1, 1954, the United States detonated a 15-megaton nuclear weapon on the Bikini Atoll, in the Marshall Islands, in a test codenamed “Castle Bravo”. It became the most powerful nuclear bomb tested by the U.S. It was detonated on the surface rather than being dropped by air. Due to a design error, the explosive energy from the bomb reached 15 megatons, two and a half times what was expected.
The mushroom cloud climbed up to roughly 25 miles (40 km). The nuclear fallout spread for about 7,000 square miles (18,130 square kilometers) across the Pacific, and inhabitants of nearby atolls were exposed to high levels of radioactive fallout. Traces of the blast were found in Australia, India, Japan, and Europe.
7. Castle Yankee (13.5 megatons)
On May 5, 1954, the United States detonated a nuclear weapon code named “Castle Yankee” on the Bikini Atoll, in the Marshall Islands. It yielded 13.5 megatons, much higher than the predicted yield of up to 10 megatons. Within four days of the blast, its fallout reached Mexico City, roughly 7,100 miles (11,400 km) away. The “Castle Yankee” is about 900 times more powerful than the one dropped on Hiroshima.
8. Test 123 (12.5 megatons)
On October 23, 1961, the Soviet Union dropped a 12.5-megaton bomb on the Novaya Zemlya archipelago, about 830 times as powerful as the Hiroshima bomb. The explosive energy was enough to vaporize everything within a 2.1-mile (3.5 km) radius.
9. Castle Romeo (11 megatons)
On March 26, 1954, a nuclear weapon was detonated on a barge off the Bikini Atoll. At 11 megatons, the test produced more than double its predicted explosive energy of 4 megatons. The yield was about 730 times as powerful as the Hiroshima bomb.
10. Ivy Mike (10.4 megatons)
On November 1, 1952, “Ivy Mike” or “Mike”, would become the first thermonuclear weapon (hydrogen bomb) to be fully detonated – yielding a 10.4-megaton explosion, about 690 times the size of the Hiroshima bomb. Hydrogen bombs rely on nuclear fusion to amplify their explosions, producing much more explosive energy than atomic bombs that use nuclear fission. It was detonated on the surface of the Enewetak atoll on the Marshall Islands.
The two bombs dropped on Hiroshima and Nagasaki had devastating consequences, and their explosive yields were only a fraction of the 10 largest explosions. The power of modern nuclear weapons makes their scale of destruction truly unfathomable, and as history suggests, the outcomes can be unpredictable.