File:Operation Crossroads Baker Edit.jpg

Summary
http://commons.wikimedia.org/wiki/File:Operation_Crossroads_Baker_Edit.jpg

The "Baker" explosion, part of Operation Crossroads, a nuclear weapon test

by the United States military at Bikini Atoll, Micronesia, on 25 July

1946. The wider, exterior cloud is actually just a condensation cloud

caused by the Wilson chamber effect, and was very brief. There was no

classic mushroom cloud rising to the stratosphere, but inside the

condensation cloud the top of the water geyser formed a mushroom-like head

called the cauliflower, which fell back into the lagoon (compare with this

image, a photo taken slightly later, after the condensation cloud had

cleared). The water released by the explosion was highly radioactive and

contaminated many of the ships that were set up near it. Some were

otherwise undamaged and sent to Hunter's Point in San Francisco,

California, United States, for decontamination. Those which could not be

decontaminated were sunk a number of miles off the coast of San Francisco.

Mushroom-shaped cloud and water column from the underwater Baker nuclear

explosion of July 25, 1946. Photo taken from a tower on Bikini Island, 3.5

miles (5.6 km) away.