Volume 67, Issue 3 p. 1027-1039

On the origin of the sodium present in the upper atmosphere

First published: March 1962
Citations: 34


Various origins are considered for the atmospheric sodium observed in the twilight and nightglow above an altitude of 70 km. The transport of sea salt to these altitudes in sufficient quantities seems impossible except in the unlikely case of complete atomization of the sodium at low altitudes (30 km). Other terrestrial sources seem even more unlikely. The sodium has not accreted from the sun, as shown by a consideration of the amount of neon now present in the atmosphere. Meteoric influx does provide sufficient quantities of atomic sodium at altitudes of 70 km and greater, and is probably the source of the airglow sodium. The influx of micrometeoritic material is capable of providing even more sodium than do the meteors, but there is great uncertainty as to the fraction of this material which vaporizes. Other metals which have been observed in the high atmosphere are Ca, Li, and Mg. However, no conclusions with regard to the origin of these constituents can be drawn from the presently available evidence.