The variation of the atomic oxygen density inferred from Ogo 6 green nightglow emission between 100 km and 120 km is too rapid to be consistent with the temperature gradients in standard model atmospheres and an eddy diffusion coefficient that reaches its maximum below 115 km. The oxygen distribution can be reconciled with a constant eddy diffusion coefficient above 100 km if the temperature gradient reaches a value between 10¿ and 20¿K/km for low values of the eddy diffusion coefficient (K~5¿105 cm2 s-1) or between 30¿ and 50¿K/km for K~1.6¿106 cm2 s-1, compared with a maximum gradient of about 10¿K/km in the Jacchia 1971 model. Such gradients as are implied by the oxygen profiles are also observed in Pitot tube experiments flown on sounding rockets and in incoherent scatter measurements. The low K profiles are also consistent with Ar/N2 ratios measured on sounding rockets and are large enough to conduct away thermally a large part of the solar energy deposited below 120 km, thereby alleviating a serious problem in disposing of this energy.