Stratus cloud classified as pannus clouds. Stratus only has one mutatus mother cloud. Stratus stratocumulomutatus clouds occur when stratocumulus opacus patches fuse to create a stratiform layer. Stratus clouds don't produce accessory clouds, but a supplementary feature praecipitatio is derived from Latin, which means "precipitation". Stratus clouds are too low to produce virga, or rain shears that evaporate before reaching the ground. A stratus cloud can form from stratocumulus spreading out under an inversion, indicating a continuation of prolonged cloudy weather with drizzle for several hours and then an improvement as it breaks into stratocumulus. Stratus clouds can persist for days in
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