Types
The "green flash" description relates to a group of optical phenomena, some of which are listed below:
| Type | Characteristics | Conditions | Best seen from... |
|---|---|---|---|
| Inferior-mirage flash | Joule's "last glimpse"; oval, flattened below; lasts 1 or 2 seconds | Surface warmer than the overlying air | Close to sea level |
| Mock-mirage flash | Indentations seem to "pinch off" a thin, pointy strip from the upper rim of the Sun; lasts 1 or 2 seconds | Atmospheric inversion layer below eye level; surface colder than air | The higher the eye, the more likely; flash is most obvious when the eye is just above the inversion. |
| Sub-duct flash | Large upper part of an hourglass-shaped Sun turns green for up to 15 seconds; | Observer below a strong atmospheric inversion | In a narrow height interval just below a duct (can occur at any height) |
| Green ray | Green beam of light either shooting up or seen immediately after sundown; usually few degrees long, lasting several seconds | Hazy air and a bright green flash acting as a light source | Sea level |
The majority of flashes observed are inferior-mirage or mock-mirage effects, with the others constituting only 1% of reports. Some types not listed in the table above, such as the cloud-top flash (seen as the sun sinks into a coastal fog, or at distant cumulus clouds), are not understood.
Read more about this topic: Green Flash
Famous quotes containing the word types:
“If there is nothing new on the earth, still the traveler always has a resource in the skies. They are constantly turning a new page to view. The wind sets the types on this blue ground, and the inquiring may always read a new truth there.”
—Henry David Thoreau (1817–1862)
“Our major universities are now stuck with an army of pedestrian, toadying careerists, Fifties types who wave around Sixties banners to conceal their record of ruthless, beaverlike tunneling to the top.”
—Camille Paglia (b. 1947)
“As for types like my own, obscurely motivated by the conviction that our existence was worthless if we didn’t make a turning point of it, we were assigned to the humanities, to poetry, philosophy, painting—the nursery games of humankind, which had to be left behind when the age of science began. The humanities would be called upon to choose a wallpaper for the crypt, as the end drew near.”
—Saul Bellow (b. 1915)