DENSITY ALTITUDE MODEL assume perfect gas and constant temperature p A d nkT p=nkT h dh n is number density (number/m )dpa-nmgadh=o dnt k is boltzmann's constant nMg= M is average molecular mass n K H84km h 120km n=nexp (-h/H) h=kT/mg(scale heighDENSITY ALTITUDE MODEL Assume perfect gas and constant temperature n is number density (number/m 3) dpA - n m g A d h = o k is Boltzmann’s constant M is average molecular mass H ~ 8.4km h ~ 120km n = n oexp (-h/H) H { kT/mg (scale height) dh d nk T dh dp p n k T ¸ ¸ ¹ · ¨ ¨ © § dh d nk T nMg dhdp ¸ ¸ ¹ · ¨ ¨ © § dh K T Mg n dn p A dh p+dp 11