Sunday, Nov 3, 2024

I am pleased to send my photographic work for your Selection: Definition of green ray (World Meteorological Organization): A predominantly green coloration of short duration, often in the form of a flash, seen at the extreme upper edge of the Sun, Moon or sometimes even a planet when disappearing below or appearing above the horizon. The phenomenon of green flash is vast and manifests itself with many shades, let's see the known cases: Green segment: term popularized by O'Connell (1950) to generically indicate the first formation of green on the horizon that precedes the final green flash (when the Sun disappears below the horizon). It subsequently fell into disuse. Green rim: green streaks that detach from the upper edge of the Sun, their formation heralds the true green ray (visible only with binoculars or a telescope), can last up to 15 seconds and is visible if the observer is in a strip of air with strong thermal inversion. It can never become blue or violet. Blue rim: Andrew T. Young claims that the blue rim does not exist, however there are conflicting opinions in the scientific community. From personal experience I can say that sometimes the green rim can appear partially bluish. Red rim: red streaks on the lower edge of the solar or lunar disk. It appears in a symmetrical position to the green rim when the star is above the horizon. Green spikes: it is a series of green rims that form simultaneously on the last visible edge of the solar disk. Easily recognizable with binoculars if the Sun sets behind a jagged ridge such as that of a tree or clouds. Green flash (the best known): it is a green rim that forms from the last visible edge of the solar disk, or when it crosses a thermal inversion layer (visible to the naked eye from the coasts). It forms in nebulous air if there are two surfaces of air with different temperatures. Green ray: faint green flash that radiates from the solar disk vertically for at least 10 degrees (very rare). Blue flash: last visible solar limb with shades of blue and indigo (visible to the naked eye from mountain tops). Green flash on sunspots: Green formations can also be observed on the lower edges of large sunspots as these are much darker than the Sun. In these cases, the green ray should not be considered on the lower part of the spot, but on the upper part of the Sun under the spot. The majority (about 2/3 or 3/4) of all observations are from an inferior mirage. The rest are from a mock mirage. This is a type of inferior mirage that generates multiple fictitious images that change shape and position over time. It differs from a simple inferior mirage because the latter generates only a fake image below the real one. Other types of flashes exist, but they are rare and constitute only 1% (of all reports). Not all types are mentioned, and there are also some not covered here, such as the cloud-top flash (usually seen when the Sun sinks into coastal fog, but sometimes also in distant cumulus clouds), or Alistair Fraser flashes, seen in hilly countryside. These are a variant of the mock mirage flash if strong ones are present (Taken from the book: Luci e Clori del Cielo, author Marco Meniero, Ronca Ed.)