Noctilucent (“night-shining”) clouds hover at the edge of Earth’s atmosphere, at altitudes of 76 to 85 km.They’re so high up that they reflect the sun even at night, producing an electric-blue glow.Now some scientists say these high-flying clouds may come with a metal lining – not made of silver, but of sodium and iron.
For the last two years, the Aeronomy of Ice in the Mesosphere (AIM) satellite mission has been studying noctilucent clouds, also known as polar mesospheric clouds.A curious property of these clouds is that they reflect radar, which scientists thought might be due to charged particles in the clouds.But new mathematical calculations published in the Journal of Geophysical Research-Atmospheres by Paul Bellan, a physicist at Caltech, suggests the reflections could be due to a thin layer of metal coating the clouds.
Bellan thinks the metal film is composed of sodium and iron because atmospheric levels of these ...
