Systems Glitch retweeted
馃寛 Fire rainbows also known as circumhorizontal arcs, are rare, natural, spontaneous, physical phenomena, explained by the quality of chemiluminescence in sodium crystals suspended in masses of water vapor that emit light at different wavelengths when heated, producing the vivid rainbow effect.
This particular atmospheric optical event happens only under certain conditions; the incident rays have to be perpendicular to the grain. The Sun needs to be high in the sky (above 58掳 altitude), and the cirrus clouds with flat, hexagonal ice crystals have to be oriented horizontally with respect to the incoming light.
The swirling vortex that often accompanies fire rainbows is due by a fluid dynamics principle, hot rising gases create a low鈥憄ressure zone that draws surrounding air into a spinning column, forming a whirl or tornado鈥憀ike structure.
Fire rainbows are most common in summer time at mid latitudes 馃寛






