Daytime and nighttime atmospheric properties derived from rocket and satellite observations

Abstract

Upper air densities obtained by means of rockets and satellites in the region from 100 to about 800 km are presented. Variations of densities from day to night become apparent around 200±30 km; the effect increases with altitude. Pressures and scale heights are derived from densities, and preliminary mean, and daytime and nighttime values are obtained. From the variation of scale height with altitude, regions of constant temperature and of variable molecular weight have been determined. It has been found that the mean temperature at about 300 km is approximately 1400°K, and that it stays constant above that altitude. Two hours after noon, at about 350 km, the temperature rises to approximately 1800°K. Shortly after midnight, the temperature drops to about 1050°K and stays approximately constant above 250 km. A change in slope of the density curve in the ionosphere is indicated from satellite observations. It is shown that, as a result of this, the scale height in the F and E regions has a pattern comparable to the electron density pattern in these regions. The possibility of a solar activity effect on densities is discussed.