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.
Atolls are at risk of becoming uninhabitable as sea levels rise, Marshall islands president will tell summit. This young boy on Funafuti atoll in Tuvalu may grow up to see his home beneath the sea without action on climate change. Photograph: Gamma-Rapho via Getty Images.