The Formation of Longitudinal Sand Dunes by Large Helical Eddies in the Atmosphere

摘要: Abstract It is suggested that helical roll vortices in the atmosphere are responsible for formation of longitudinal sand dunes cover over half area large deserts world. The aligned direction prevailing wind and spaced ∼2 km apart. Observations laboratory, hydrodynamic stability theory, indicate dominant forms motion boundary layer counter-rotating along having diameters approximately equal to thickness layer. necessary conditions these fulfilled their spacings agree with observed dunes.