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.
Life Span Without Food. Nits, or lice eggs, canât live without a human host. They need the warmth of the scalp for incubation purposes before they hatch. Once theyâve hatched, they need the nourishment they get from human blood.Nits that are dislodged from a hair shaft will most likely die before they hatch.arasites need a host to provide nourishment so they can live. Head lice form a parasitic relationship with humans as their host, with blood from the scalp as their source of nourishment. Head lice live close to the scalp, and sometimes the eyelashes and eyebrows.