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.
The habitable zone, also known as the âGoldilocks Zoneâ, is the region around a star where the average temperature on a planet allows for liquid water with which to make porridge. Itâs that liquid water that we hunt for not only for our future uses, but as an indicator of where alien life could be in the Universe.