Terrifying Potential.

Since the Cold War, thousands of nuclear weapons have been tested by the world's nuclear powers United States, Russia, France, China, Great Britain, Israel, India, and Pakistan. (though the vast majority were tested by the US and Russia) many which dwarfed the bombs dropped on Japan.
A modern nuclear weapon has the yield of around 1 megaton(10,000 tons) of TNT, or 50 times the yield of the Nagasaki bomb. The damage from the nuclear bomb is usually caused by the shock wave, which can reach speeds of anywhere from 800 mph (at Hiroshima) to an astonishing 2000 mph, as at the Russian Tsar Bomb test, the largest in history. The amount of pressure exerted by the blast wave is measured in PSI, or pounds per square inch. Overpressures of 10-15 pounds per square inch in sufficient enough to level concrete buildings. At Hiroshima, overpressures of around 10 psi were observed in a half mile radius, with complete destruction(5 psi) extending for about a mile.(effects of a nuclear blast wave in Chinese test) Complete destruction was observed for almost 30 miles at the Tsar Bomb test, with partial destruction 20 miles further. Overpressures of 300 psi were under the fireball(it was detonated 10,000 feet above ground.) The mushroom cloud topped out at 200,000 feet, the detonation itself was about 50 megatons, 2000 times as powerfull as the bomb dropped over Nagasaki (it was capable of 100 megatons). This is 10 times the amount of explosives used in Word War II. Windows were shattered 700 miles away. Video of the test is below


The radiant heat from the fireball is devastating to people and buildings that are surrounding. The heat, which at the point of detonation is anything from 50 million to 500 million degrees fahrenheit, is easily enough to vaporize anything too close. At Hiroshima, several thousand victims were never found, because of their vaporization.
Most of the subsequent effects come from nuclear fallout. Nuclear fallout is radioactive dust and other particles that fall are blown around by natural winds. In large tests, fallout can travel hundreds of miles, poisoning civilians and causing cancer. In the 1950s at Bikini Atoll in Micronesia, fallout from US nuclear tests sickened hundreds of individual islanders and forces a mass evacuation of the surrounding islands. The Tsar Bomb, was designed to have almost zero fission, which significantly reduced the amount of fallout. Extremely high yield bombs could have fallout that could have long term effects on the ecology of the area denonated near.
One of the most controversial long term aspects of a high yield nuclear test, is a nuclear winter. The nuclear winter theory states that in a massive nuclear detonation, a large amount of dust and debris will fill the atmosphere, and reflect the sunlight, causing a global winter. Most researchers agree however, that there could simply not enough dust kicked up, even in large tests to have any effect on the climate. This has occurred large volcanic eruptions though, which hurl much larger quantities of ash and dust into the air than nuclear explosions. Mount Tambora on April 10, 1815 exploded with force of over 500 megatons of TNT, and threw enough volcanic ash into the atmosphere to significantly effect the earth's climate. A global famine ensued in 1816, caused by severe mid summer frosts and snow being reported worlwide. It was recongnized as the worst famine of the 19th century. Though large volcanic eruptions can dwarf the energy produced in large nukes, large eruptions are rare, while powerful nukes are common worldwide. Nukes also have a much greater destructive potential from their shock wave and heat.