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The omega equation is of great importance in meteorology and atmospheric physics. It is a partial differential equation for the vertical velocity, , which is defined as a Lagrangian rate of change of pressure with time, that is, . The equation reads: : where is the Coriolis parameter, is the static stability, is the geostrophic velocity vector, is the geostrophic relative vorticity, is the geopotential, is the horizontal Laplacian operator and is the horizontal del operator.〔Holton, J.R., 1992, ''An Introduction to Dynamic Meteorology'' Academic Press, 166-175〕 ==Derivation== The derivation of the equation is based on the vorticity equation and the thermodynamic equation. The vorticity equation for a frictionless atmosphere may be written as: : Here is the relative vorticity, the horizontal wind velocity vector, whose components in the and directions are and respectively, the absolute vorticity, the Coriolis parameter, the individual rate of change of pressure . is the unit vertical vector, is the isobaric Del (grad) operator, is the vertical advection of vorticity and represents the transformation of horizontal vorticity into vertical vorticity.〔Singh & Rathor, 1974, Reduction of the Complete Omega Equation to the Simplest Form, Pure and Applied Geophysics, 112, 219-223〕 The thermodynamic equation may be written as: : where , in which is the supply of heat per unit-time and mass, the specific heat of dry air, the gas constant for dry air, is the potential temperature and is geopotential . The equation () is then obtained from equation () and () by substituting values: : and : into (), which gives: : Differentiating () with respect to gives: : Taking the Laplacian () of () gives: : Adding () and (), simplifying and substituting , gives: : Equation () is now a linear differential equation in , such that it can be split into two part, namely and , such that: : and : where is the vertical velocity due to the mean baroclinicity in the atmosphere and is the vertical velocity due to the non-adiabatic heating, which includes the latent heat of condensation, sensible heat radiation, etc. (Singh & Rathor, 1974). 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Omega equation」の詳細全文を読む スポンサード リンク
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