boundary layer
1. At the interface between a solid surface and a fluid, a thin fluid layer that is static because of friction between molecules of the fluid and the solid.

2. General term used to describe the atmospheric layer up to about 100 m above the ground surface, where the air flow is largely conditioned by the frictional effects of the surface. Mean velocities in the boundary layer are typically less than the free-stream values. See also PLANETARY BOUNDARY LAYER.

boundary layer The atmospheric layer up to about 100 m above the ground surface, where the air flow is largely conditioned by the frictional effects of the surface. Mean velocities in the boundary layer are typically less than the free-stream values.