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.
They calculated that Earth's habitable-zone lifetime is as long as 7.79 billion years. (Earth is estimated to be about 4.5 billion years old.) Meanwhile, the other planets had habitable-zone lifetimes ranging from 1 billion years to 54.72 billion years.If we ever needed to move to another planet, Mars is probably our best bet, Rushby said in a statement.Earth is estimated to be about 4.5 billion years old.) Meanwhile, the other planets had habitable-zone lifetimes ranging from 1 billion years to 54.72 billion years. If we ever needed to move to another planet, Mars is probably our best bet, Rushby said in a statement.