Difficult to observe, the momentary green flash [
http://www.exo.net/…green_flash.html ] above the rising or setting sun has been documented as [
http://mintaka.sdsu…] a phenomenon caused by the atmospheric bending or refraction of sunlight. Like a weak prism, the Earth's atmosphere breaks white sunlight [
http://micro.magnet…index.html ] into colors, bending red colors slightly and green and blue colors through increasingly larger angles [
http://micro.magnet…scienceopticsu/refra ction/index.html ]. When the sky is clear, a green flash [
http://www.physics.…sandiego.html ] just above the sun's edge can sometimes be seen for a second or so, when the sun is close to a distant horizon. A blue flash is even harder to see though, because the atmosphere [
http://antwrp.gsfc.…] must be extraordinarily clear to avoid scattering and diminishing the refracted blue sunlight. Still, from a site near Roques de los Muchachos (altitude 2,400 meters) on La Palma in the Canary Islands [
http://antwrp.gsfc.…], astrophotographer Mario Cogo captured this dramatic telescopic image of a blue flash on color film in October of 2001. The image of the setting Sun with large sunspot groups [
http://antwrp.gsfc.…] on its surface is heavily distorted by atmospheric layers. A lingering green rim is just visible under the tantalizing blue flash.
Explanation
Difficult to observe, the momentary green flash [
http://www.exo.net/…green_flash.html ] above the rising or setting sun has been documented as [
http://mintaka.sdsu…] a phenomenon caused by the atmospheric bending or refraction of sunlight. Like a weak prism, the Earth's atmosphere breaks white sunlight [
http://micro.magnet…index.html ] into colors, bending red colors slightly and green and blue colors through increasingly larger angles [
http://micro.magnet…scienceopticsu/refra ction/index.html ]. When the sky is clear, a green flash [
http://www.physics.…sandiego.html ] just above the sun's edge can sometimes be seen for a second or so, when the sun is close to a distant horizon. A blue flash is even harder to see though, because the atmosphere [
http://antwrp.gsfc.…] must be extraordinarily clear to avoid scattering and diminishing the refracted blue sunlight. Still, from a site near Roques de los Muchachos (altitude 2,400 meters) on La Palma in the Canary Islands [
http://antwrp.gsfc.…], astrophotographer Mario Cogo captured this dramatic telescopic image of a blue flash on color film in October of 2001. The image of the setting Sun with large sunspot groups [
http://antwrp.gsfc.…] on its surface is heavily distorted by atmospheric layers. A lingering green rim is just visible under the tantalizing blue flash.
Explanation
