The surface layer
is the layer of a turbulent fluid most affected by interaction with a solid surface or the surface separating a gas and a liquid. In surface layers the characteristics of the turbulence
depend on distance from the interface. Surface layers are characterized by large normal gradients of tangential velocity and large concentration gradients of any substances (temperature, moisture, sediments etc.) transported to or from the interface. The term is most used in meteorology
. The atmospheric surface layer is the lowest part of the atmospheric boundary layer
(typically the bottom 10% where the log wind profile
is valid), and the benthic surface layer is the layer found immediately above the sea floor. An atmospheric surface layer is found above an air-sea interface and a marine surface layer beneath one.