Low-level surface winds:
The surface and low level winds are weak in the case of Radiation fog Advection fog . If the surface and low level winds are moderate or even strong the Fog/Stratus is more likely to be Radiation fog Advection fog . A strong shear in the boundary layer is also is not a key parameter for Fog and Stratus.Surface temperature:
A temperature difference between the surface and moist dry air flow above are precursors of Fog and Stratus. Wet Dry snow cover acts in the same manner as cold sea surface by enhancing the formation of fog.