Concept

Green flash

The green flash and green ray are meteorological optical phenomena that sometimes occur transiently around the moment of sunset or sunrise. When the conditions are right, a distinct green spot is briefly visible above the Sun's upper limb; the green appearance usually lasts for no more than two seconds. Rarely, the green flash can resemble a green ray shooting up from the sunset or sunrise point. Green flashes occur because the Earth's atmosphere can cause the light from the Sun to separate, or refract, into different colors. Green flashes are a group of similar phenomena that stem from slightly different causes, and therefore, some types of green flashes are more common than others. Green flashes may be observed from any altitude. They usually are seen at an unobstructed horizon, such as over the ocean, but are possible over cloud tops and mountain tops as well. They may occur at any latitude, although at the equator, the flash rarely lasts longer than a second. The green flash also may be observed in association with the Moon and bright planets at the horizon, including Venus and Jupiter. With an unrestricted view of the horizon, green flashes are regularly seen by airline pilots, particularly when flying westwards as the sunset is slowed. If the atmosphere is layered, the green flash may appear as a series of flashes. While observing at the Vatican Observatory in 1960, D.J.K. O'Connell produced the first color photograph of the green flash at sunset. Green flash occurs because the atmosphere causes the light from the Sun to separate, or refract, into different frequencies. Green flashes are enhanced by mirages, which increase refraction. A green flash is more likely to be seen in stable, clear air, when more of the light from the setting sun reaches the observer without being scattered. One might expect to see a blue flash, since blue light is refracted most of all and the blue component of the sun's light is therefore the last to disappear below the horizon, but the blue is preferentially scattered out of the line of sight, and the remaining light ends up appearing green.

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Mirage
A mirage is a naturally-occurring optical phenomenon in which light rays bend via refraction to produce a displaced image of distant objects or the sky. The word comes to English via the French (se) mirer, from the Latin mirari, meaning "to look at, to wonder at". Mirages can be categorized as "inferior" (meaning lower), "superior" (meaning higher) and "Fata Morgana", one kind of superior mirage consisting of a series of unusually elaborate, vertically stacked images, which form one rapidly-changing mirage.
Fata Morgana (mirage)
A Fata Morgana (ˈfaːta morˈɡaːna) is a complex form of superior mirage visible in a narrow band right above the horizon. The term Fata Morgana is the Italian translation of "Morgan the Fairy" (Morgan le Fay of Arthurian legend). These mirages are often seen in the Italian Strait of Messina, and were described as fairy castles in the air or false land conjured by her magic. Fata Morgana mirages significantly distort the object or objects on which they are based, often such that the object is completely unrecognizable.
Sunrise
Sunrise (or sunup) is the moment when the upper rim of the Sun appears on the horizon in the morning. The term can also refer to the entire process of the solar disk crossing the horizon and its accompanying atmospheric effects. Although the Sun appears to "rise" from the horizon, it is actually the Earth's motion that causes the Sun to appear. The illusion of a moving Sun results from Earth observers being in a rotating reference frame; this apparent motion caused many cultures to have mythologies and religions built around the geocentric model, which prevailed until astronomer Nicolaus Copernicus formulated his heliocentric model in the 16th century.
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