Stratus cloud a region. Some call these clouds "high fog" for the fog-like cloud. While light rain may fall, this cloud does not indicate much meteorological activity. Stratus clouds form when a sheet of warm, moist air lifts off the ground and depressurizes, following the lapse rate. This causes the relative humidity to increase due to the adiabatic cooling. Stratus clouds look like featureless gray to white sheets of cloud. They can be composed of water droplets, supercooled water droplets, or ice crystals depending upon the ambient temperature. Stratus nebulosus clouds appear as a featureless or nebulous veil or layer of stratus
Vortex sheet of a vortex sheet by vortex panels with arc wise diffusion of circulation density also shows that the sheet rolls-up into a double branched spiral. In many engineering and physical applications the growth of a temporal free shear layer is of interest. The thickness of a free shear layer is usually measured by momentum thickness, which is defined as formula_28 where formula_29 and formula_30 is the freestream velocity. Momentum thickness has the dimension of length and the non-dimensional momentum thickness is given by formula_31. Momentum thickness can be used to measure the thickness of a vortex layer. Vortex sheet A