The object of this research is to explore how wavelike disturbances are created in the lower atmosphere, how these waves contribute to turbulence and mixing, and how these waves influence the location of severe weather events such as storms and squall lines. The waves of intent are gravity waves, ordered disturbances with wavelengths ranging from a few hundred meters to many hundreds of kilometers, and periods ranging from a few minutes to large fractions of a day. The scales of these waves and some other physical characteristics allow them to interact strongly with meteorological systems such as storms, gusts, squall lines, and the turbulence that leads to atmospheric mixing. The importance of these waves in meteorology has been recognized since the 1950's, but the challenge of learning how to apply the wave theory to practical situations remains. The wave theory itself is still incomplete, particularly with respect to the origin of many of the waves and how they behave when they reach large amplitudes. This proposal studies a wave generation mechanism that receives attention in engineering applications, but has been rather neglected in meteorology, Jeffreys' drag mechanism. The mechanism originates with the friction that a fluid experiences as it moves over a rough surface - in the meteorological context, the surface of the earth. The disparate natures of the forces that drive the motion of the fluid and the surface forces that oppose the flow can result in a breakdown of basic flows parallel to the surface: wavelike disturbances appear in the flow, extracting energy from the forces that drive the motion. Previous studies of this process suggest that it may be very effective in producing the atmospheric waves that break to produce mixing and turbulence. The studies also indicate that the process contributes to the strong, larger-scale waves associated with bands of severe weather. The theory will be developed further and used to interpret particular meteorological events, prob ably in the Southeast.
