Properties of the turbulent cloud-clear air interface observed in the laboratory experiment

Abstract

Two-dimensional horizontal and vertical cuts through patterns created in the process of turbulent mixing of a cloud with unsaturated clear air are imaged in the laboratory experiment. The extracted cloud-clear air interface is then investigated in terms of a modified box-counting analysis. Results indicate that the observed interface scales in the range 2×10−2 to 5×10−1, and is not self-similar in scales below 2×10−2 m. The detailed analysis shows that the scaling exponents in the horizontal and vertical are not equal. An interface scales rather like a product of independent sets than according to the additive codimension rule, which is the case for isoconcentration surfaces of passive scalars in typical turbulent flows. Based on the above results alternative estimates of the area of the cloud-clear interface are proposed.