渦動對積雲形成之影響

王業鈞　徐士哲　程為莉

On the Influence of Eddy Mixing on the Formation and Development of Cumulus Cloud

John Y.C. Wang　S.C. Hsu　W.L. Chen

Abstract

　　The influence of eddy mixing on the formation and the development of cumulus clouds have been studied; using Wang’s quasi-one-dimensional time-dependent, non-precipitation model which has a source of constant strength. The coefficients of the pre-existing atmospheric turbulence (ν_r) and the turbulence created by the clouds (β) themselves have been treated as variables.
　　According to the results, the two critical values of Ws concerning cloud formation are very sensitive to the variation of the pre-existing atmospheric turbulence, but not so sensitive to the turbulence created by the cloud. Other condition being fixed, the upper critical value will not be quite obvious when ν_r is greater than or equal to 1.3. If the value of ν_r exceed 9.1, the lower critical value will disappear, which means that no cloud can be developed. Furthermore, as β increases, the increment of lower critical value is found to increase. However, the increment of lower critical value is rather insignificant.