Sodium layer
With sodium layer , engl. Sodium layer is an area of the mesosphere in which there are unbound , non- ionized sodium atoms . The sodium layer is typically located at a height of 80 to 105 km and has a vertical extent of about 5 km; below that, sodium is mostly chemically bound, most often as sodium oxide , above it is ionized.
The sodium atoms are predominantly in the excited state and have a slightly yellowish radiation at a wavelength of 589 nm, the Fraunhofer sodium D line . This radiation is also known as night glow . The sodium comes from the abrasion of meteors .
The sodium layer was discovered by Vesto Melvin Slipher in 1929 , and in 1939 Sydney Chapman proposed a reaction cycle to explain the night glow.
In astronomy , the sodium layer is used to create artificial guide stars by means of lasers , which can be used to compensate for the deterioration in the image quality of telescopes caused by atmospheric turbulence ( seeing ).
Web links
- Metallic vapor layers (English)