Nuclear submarine nuclear-powered submarine was first proposed in the United States Navy by the Naval Research Laboratory's Ross Gunn in 1939. Construction of the world's first nuclear powered submarine was made possible by the successful development of a nuclear propulsion plant by a group of scientists and engineers at the Naval Reactors Branch of the Bureau of Ships and the Atomic Energy Commission. In July 1951 the U.S. Congress authorized construction of the first nuclear-powered submarine, "Nautilus", under the leadership of Captain Hyman G. Rickover, USN (sharing names with Captain Nemo's fictional submarine in Jules Verne's "Twenty Thousand Leagues Under the Sea",
Ice cap climate polar and there are some communities that are situated in a transitional zone between the two climates, but barely qualify as a tundra. Some places like Antarctica had a different climate before having an ice cap climate. Under the Köppen climate classification, the ice cap climate is denoted as "EF". Ice caps are defined as a climate with no months above . Such areas are found around the north and south pole, and on the top of the highest mountains. Since the temperature never exceeds the melting point of ice, any snow or ice that accumulates remains there permanently, over