Twice a day, at dusk and just before dawn, a faint layer of sodium and other metals begins sinking down through the atmosphere, about 90 miles high above the city of Boulder, Colorado. The movement was captured by one of the world’s most sensitive “lidar” instruments and reported today in the AGU journal Geophysical Research Letters.
Click here for original story, Atmospheric metal layers appear with surprising regularity
Source: Phys.org