Literally, in order for a vortex to be classified as a tornado, it must be in contact with the ground and the cloud base. Weather scientists haven't found it so simple in practice, however, to classify and define tornadoes (per this essay by Doswell).
Bikini Island, 2015. Credit: Emlyn Hughes. (Phys.org)âA team of researchers from Columbia University in New York has found that all of the Marshall Islands involved in nuclear tests by the U.S. are now habitable, except for Bikini Atoll.
Another possible explanation is that the bikini leaves its wearer nearly bare, the way the bomb tests stripped Bikini atoll. In 1985, the tankini began appearing on beaches in the U.S., and the word bikini was combined with tank to create its appropriate name.