Le problème des hauteurs d'échelle et de leurs gradients dans l'hétérosphère

The properties of the heterosphere are discussed in terms of the behaviour of scale heights and their gradients. The height variation of the mean molecular mass leads to important gradients of scale heights in the isothermal region of the heterosphere. An analysis of the atmospheric scale height H and the density scale height Hρ which increase with altitude shows that H ≥ Hρ everywhere. Their positive gradients β and βρ may have all possible values between 0 and 1.5. The gradient βρ is not less than β in the thermosphere, but may be greater or less than β in the isothermal region depending on the thermopause temperature.