Evolution of Snow-Size Spectra in Cyclonic Storms. Part II: Deviations from the Exponential Form

Using a form of the stochastic collection equation, conservation equations for the first and second moments of the mass were parameterized to yield a height dependent one-dimensional snow growth model for unrimed stratiform snowfall. Snow-size distributions were represented by the form N(D) = N0Dν exp(−λD), and solutions for λ and N0 were obtained. The spectral parameter ν allows the concentration of the smaller ice particles to deviate from the exponential form and controls the degree of subexponential or superexponential behavior. The sub- and superexponential spectra analyzed in this study had ν values of 1 and −1, respectively. A number of simple analytical relationships was developed that describes various properties of size distributions, regardless of the particle type involved. A method was developed for obtaining the three parameters of the size distribution used in the model from measured size distributions. In addition, an expression was derived to relate the two λ of an exponentially ...