Variations of atmospheric properties with time and solar activity

Abstract

Variations of atmospheric properties with time and solar activity have been determined from results available at present. These are primarily densities derived from the variation of orbital decelerations which are due to atmospheric drag. For medium solar activity, the possible variation of density over 24 hr periods at 350 and 650 km is shown. For the same altitudes, the possible hourly variations which might occur during high and low solar activities have been studied. As a result of these investigations, it is shown that the density for the same altitude at night (about 2 hr before local sunrise), during minimum solar activity, may vary by a factor of 200 when compared with the density occurring during the day (about 2 hr after local noontime) during solar maximum activity. Pressure, scale height, molecular weight, temperature and thermal heat flow variations, which may occur during medium solar activity over a 24 hr period at 350 and 650 km, have been derived from maximum and minimum densities and molecular weights at these altitudes, which were accepted in the CIRA 1961 tables. The 24 hr temperature variations, which may occur at 650 km, are compared with experimental results obtained by other scientists. The theoretical values presented here agree fairly well with experimental results. The temperature difference between day and night is about 700°K.