Radiative Heat Transfer and Hydrostatic Stability in Nocturnal Fog

We have performed a one-dimensional and transient radiative heat transfer analysis in order to investigate interaction between atmospheric radiation and convective instability within a nocturnal fog. The radiation element method using the Ray Emission Model (REM2), which is a generalized numerical method, in conjunction with a line-by-line (LBL) method, is employed to attain high spectral resolution calculations for anisotropically scattering fog. The results show that the convective instability has a strong dependence on radiative properties of the fog. For the condition of a 20-μm droplet diameter and liquid water content of 0.1 × 10−3 kg m−3;, the temperature profile within the fog becomes “S” shaped, and a convective instability layer forms in the middle or lower level of the fog. However, for the same water content and a 40-μm diameter droplet, no strong convective instability layer forms, whereas for a 10-μm diameter droplet a strong convective instability is observed.