]> Advection The process of transport solely by the mass motion (velocity field); also, the rate of change of the value of the advected property at a given point. That property of an object that enables it to float on the surface of a liquid, or ascend through and remain freely suspended in a compressible fluid such as the atmosphere. In general, mass motions within a fluid resulting in transport and mixing of the properties of that fluid. Convection, along with conduction and radiation, is a principal means of energy transfer. Processes by which traces gases or particles are transferred from atmosphere to a surface. A form of convection driven by a combination of gravitational and centrifugal forces. Advection of vorticity by the total wind or force. The vertical kinematic flux of virtual potential temperature, which when multiplied by the buoyancy parameter yields a flux that is proportional to buoyancy. A vertical velocity scale for convective boundary layers, that is related to the buoyant driving force for convection and the depth of the mixed layer. An average vertical transport of mass for a field, e.g., of cumulus clouds or thermals. (Also called coefficient of diffusion.) The ratio of the flux of a conservative property through a specified surface by turbulence to the gradient of the mean property normal to the surface. Diffusivity The exchange coefficient for the diffusion of a conservative property by eddies in a turbulent flow. The rate of transfer of a conservative fluid property through a surface by turbulent eddies. The rate of flow of some quantity, often used in reference to the flow of some form of energy. Transport of a quantity by quasi-random eddies or swirls; the covariance between a velocity component and any variable. Diffusion or dispersion due to the effects of turbulent motions. An imaginary volume of fluid to which may be assigned various thermodynamic and kinematic quantities.