The formula is used to measure the speed of ocean waves, like tsunamis, that have very long wavelengths relative to the depth of the water. Tsunamis can have wavelengths greater than 700 kilometers (the average ocean depth is 3-4 kilometers). The formula estimates the tsunami's speed while it is in deeper waters (as it approaches shallower coastal waters, the tsunami slows down, its wavelength shortens, and its height increases).
Head lice and their eggs (nits) soon perish if separated from their human host. Adult head lice can live only a day or so off the human head without blood for feeding. Nymphs (young head lice) can live only for several hours without feeding on a human.
Nymphs and fully mature adults can survive for only about a day without a food source. Adult lice canât live past 24 hours or so on non-human surfaces such as carpets, hardwood flooring, clothing, furniture, sports helmets, headphones, or hair accessories.onât Worry. Getting rid of a case of head lice can be time-consuming and tedious, but itâs not a health hazard. Lice donât carry disease and donât harm the head or scalp. Prevent head lice by not sharing combs, hairbrushes, hair accessories, towels, bedding, hats, or scarves with a person infected with the parasite.