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.
Moorea Tourism: Best of Moorea. Moorea, French Polynesia. The world's largest coral reef eco-system actually consists of 3,000 separate reefs. The island of Moorea serves as the perfect base camp for snorkelers and scuba divers seeking to come face-to-face with the diversity of life that darts among the coral. Non-swimmers can enjoy the same parade of astounding creatures from the dry perch of a glass-bottomed boat.