The transfer of sensible heat through a surface of unit area during a unit of time by turbulent fluid motions. Even though lightning and heavy rainfall may occur from such storms, they are not directly considered as criteria for National Weather Service severe thunderstorm warnings. A separate flash flood warning may be issued if heavy rain occurs. In plane parallel flow the motion will become unstable if the shear is sufficiently large. Large shears can lead to flow instabilities.
Shear stress is a function of the viscosity of the fluid.
Usually refers to the degree of accuracy or improvement that a personal weather forecast has compared to that of forecasts based on chance, persistence, or climatology alone. The pellets may be spherical or irregular in shape and are either translucent or transparent. A combination of smoke and photochemically created pollution with or without fog. It is often associated with urban areas where automobile hydrocarbon and nitric oxide emissions and coal-burning power plant sulfur dioxide emissions can be large. Smog is made of phytotoxic chemicals, skin irritants, and lung irritants which may aggravate persons with breathing problems.