Image: United States Department of Energy
Ivy Mike’s raging spherical fireball was around 3.25 miles (5.2 km) wide. Its mushroom cloud soared to 57,000 ft (17.0 km) in just 90 seconds, entering the stratosphere, and one minute later reached 108,000 ft (33.0 km), before stabilising at 120,000 ft (37 km); the crown eventually stretched 100 miles (160 km) across with a stem 20 miles (32 km) wide. The nature of the device was such that it produced large quantities of fallout, lethal radioactive particles raining down on Earth.