Atmospheric Boundary Layer

The atmospheric boundary layer is the lowest part of the troposphere, where friction, heat, and moisture exchange with the surface control the flow. Over the ocean it ranges from a few hundred meters in stable, cool-advection conditions to over 1 km in convective regimes. Wind turns and accelerates with height from the surface to the geostrophic flow above, following the Ekman spiral, while turbulent eddies mix momentum, heat, and water vapor. Its depth, stability, and surface fluxes set near-surface wind speed, fog and stratus formation, and the drag the sea exerts on the air.