Astro*Dictionary
by Michael Erlewine

1 article for
"D-region"

Lowest ionospheric region, at altitudes of about 70 to 90 km (40 to 55 miles). The D-region differs from the other ionospheric regions (denoted E and F) in that its free electrons almost totally disappear during the night because they recombine with oxygen ions to form oxygen molecules.

 

See also:
♦ Atmosphere of Earth