Note on cellular convection with nonisotropic eddies

Abstract

“According to Krueger and Fritz (1961). one of the outstanding features calling for explanation in the cellular cloud patterns revealed by satellites is that the diameter-to-depth ratio i s around 30, instead of about 3 as predicted by classical theory and verified by laboratory experiments.” This call for explanation in the introductory sentence of a short communication by Priestley (1962) is as urgent today as 21 years ago. He advocated and Ray (1965) calculated the influence of anisotropic eddy dilfusion as a possible solution to the problem of cell flatness. Using the classical Boussinesq approximation to describe Rayleigh-Benard convection and introducing turbulent horizontal heat and momentum dilfusion coefficients of about 100 times the vertical value, results in cell aspect ratios of the required magnitude. This was confirmed recently by Sheu et al. (1980) making eddy anisotropy a major candidate for explanation of the dilference between observation and theory (also Agee and Mitchell, 1977).