中高层大气物理学第一章Simlemodels简单模型.ppt

LOGO 2011 PHYSICS OF THE MIDDLE AND UPPER ATMOSPHERE中高层大气物理学Simple Models Atmosphere in Isothermal Equilibrium Assume the atmosphere is at rest, uninfluenced by any external agency. Since the conduction of heat from one region to another is slow, after certain time an uniform temperature will be established. Then the atmosphere can be described as: ρ attains zero value at infinity. The atmosphere extends to infinity. Stratosphere has a tendency to attain this isothermal equilibrium. Atmosphere in Adiabatic Equilibrium An adiabatic equilibrium tends to be set up if the atmosphere is subjected to turbulence and convective motions. Gases do not lose or gain heat at they move but take up the requisite temperatures and pressures in their new positions. density decreases with height and becomes zero at This happens for the troposphere of the Earth’s atmosphere. Linear T variation with altitude α can be positive as in the stratosphere and thermosphere and negative as in the troposphere and the mesosphere. pressure and the density will not have the same variation by altitude. Isothermal, g varies Reference level z0 z → ∞ Linear T, g varies Reference level z0 z → ∞ T profile of Jacchia 1965 Where z0 = 120km and T∞ is the asymptotic (exospheric) temperature. Exercises:Integrate with constant g and altitude dependent g, respectively. 定亚比热,定容比热，绝热指数where γ (= cp/cv) is the adiabatic constant. * LOGO 定亚比热,定容比热，绝热指数where γ (= cp/cv) is the adiabatic constant. *