|
False Sunset
A false sunset can refer to one of two related atmospheric optical phenomena, in which either (1) the Sun appears to be setting into or to have set below the horizon while it is actually still some height above the horizon, or (2) the Sun has already set below the horizon, but still appears to be on or above the horizon (thus representing the reverse of a false sunrise). Depending on circumstances, these phenomena can give the impression of an actual sunset. There are several atmospheric conditions which may cause the effect, most commonly a type of halo, caused by the reflection and refraction of sunlight by small ice crystals in the atmosphere, often in the form of cirrostratus clouds. Depending on which variety of "false sunset" is meant, the halo has to appear either above the Sun (which itself is hidden below the horizon) or below it (in which case the real Sun is obstructed from view, e.g. by clouds or other objects), making the upper and lower tangent arc, upper and l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atmospheric Optics
Atmospheric optics is "the study of the optical characteristics of the atmosphere or products of atmospheric processes .... [including] temporal and spatial resolutions beyond those discernible with the naked eye". Meteorological optics is "that part of atmospheric optics concerned with the study of patterns observable with the naked eye". Nevertheless, the two terms are sometimes used interchangeably. Meteorological optical phenomena, as described in this article, are concerned with how the optical properties of Earth's atmosphere cause a wide range of optical phenomena and visual perception phenomena. Examples of meteorological phenomena include: *The diffuse sky radiation, blue color of the sky. This is from Rayleigh scattering, which redirects higher frequency/shorter wavelength (blue) sunlight back into the field of view of the observer. *The reddish color of the Sun when it is observed through a air mass (astronomy), thick atmosphere, as during a sunrise or sunset. This is b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Upper Tangent Arc
Tangent arcs are a type of halo, an atmospheric optical phenomenon, which appears above and below the observed Sun or Moon, tangent to the 22° halo. To produce these arcs, rod-shaped hexagonal ice crystals need to have their long axis aligned horizontally. Description Upper arc The shape of an upper tangent arc varies with the elevation of the Sun; while the Sun is low (less than 29–32°) it appears as an arc over the observed Sun forming a sharp angle. As the Sun is seen to rise above the Earth's horizon, the curved wings of the arc lower towards the 22° halo while gradually becoming longer. As the Sun rises over 29–32°, the upper tangent arc unites with the lower tangent arc to form the circumscribed halo. Lower arc The lower tangent arc is rarely observable, appearing under and tangent to a 22° halo centred on the Sun. Just like upper tangent arcs, the shape of a lower arc is dependent on the altitude of the Sun. As the Sun is observed slipping over Earth' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Light Pillar
A light pillar is an atmospheric optical phenomenon in which a vertical beam of light appears to extend above and/or below a light source. The effect is created by the reflection of light from tiny ice crystals that are suspended in the atmosphere or that comprise high-altitude clouds (e.g. cirrostratus or cirrus clouds).Colonne lumineuse by the . If the light comes from the Sun (usually when it is near or even below the horizon), the phenomenon is called a sun pillar or sola ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subsun
A subsun (also spelled sub-sun) is an optical phenomenon that appears as a glowing spot visible within clouds or mist when observed from above. The subsun appears directly below the actual Sun, and is caused by sunlight reflecting off of numerous tiny ice crystals suspended in the atmosphere. As such, the effect belongs to the family of halos. The region of ice crystals acts as a large mirror, creating a virtual image of the Sun appearing below the horizon, analogous to the Sun's reflection in a body of water. The ice crystals responsible for a subsun are typically in the shape of flat hexagonal plates. As they fall through the air, their aerodynamic properties cause them to orient themselves horizontally, i.e., with their hexagonal surfaces parallel to the Earth's surface. When they are disturbed by turbulence, however, the plates start to "wobble", causing their surfaces to deviate some degrees from the ideal horizontal orientation, and causing the reflection (i.e., the s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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. In contrast to a hallucination, a mirage is a real optical phenomenon that can be captured on camera, since light rays are actually refracted to form the false image at the observer's location. What the image appears to represent, however, is determined by the interpretive faculties of the human mind. For example, inferior images on land are very easily mistaken for the reflections from a small body of water. Inferior mirage In an inferior mirage, the mirage ima ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lower Tangent Arc
Tangent arcs are a type of halo, an atmospheric optical phenomenon, which appears above and below the observed Sun or Moon, tangent to the 22° halo. To produce these arcs, rod-shaped hexagonal ice crystals need to have their long axis aligned horizontally. Description Upper arc The shape of an upper tangent arc varies with the elevation of the Sun; while the Sun is low (less than 29–32°) it appears as an arc over the observed Sun forming a sharp angle. As the Sun is seen to rise above the Earth's horizon, the curved wings of the arc lower towards the 22° halo while gradually becoming longer. As the Sun rises over 29–32°, the upper tangent arc unites with the lower tangent arc to form the circumscribed halo. Lower arc The lower tangent arc is rarely observable, appearing under and tangent to a 22° halo centred on the Sun. Just like upper tangent arcs, the shape of a lower arc is dependent on the altitude of the Sun. As the Sun is observed slipping over Earth' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Halo (optical Phenomenon)
A halo is an optical phenomenon produced by light (typically from the Sun or Moon) interacting with ice crystals suspended in the atmosphere. Halos can have many forms, ranging from colored or white rings to arcs and spots in the sky. Many of these appear near the Sun or Moon, but others occur elsewhere or even in the opposite part of the sky. Among the best known halo types are the circular halo (properly called the 22° halo), light pillars, and sun dogs, but many others occur; some are fairly common while others are extremely rare. The ice crystals responsible for halos are typically suspended in cirrus or cirrostratus clouds in the upper troposphere (), but in cold weather they can also float near the ground, in which case they are referred to as diamond dust. The particular shape and orientation of the crystals are responsible for the type of halo observed. Light is reflected and refracted by the ice crystals and may split into colors because of dispersion. The crystals ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
False Sunrise
A false sunrise is any of several atmospheric optical phenomena in which the Sun appears to have risen, but is actually still some distance below the horizon. A number of different atmospheric conditions can be responsible for this effect, all of which divert the sunlight in such a way as to allow it to reach the observer's eye, thereby giving the impression that the light comes directly from the Sun itself. The spread of light can sometimes be deceivingly similar to a true sun. Several atmospheric phenomena that may alternatively be called a "false sunrise" are: * Simple reflection of the sunlight off the bottom of the clouds. * A type of ice crystal halo, such as an upper tangent arc or, more commonly, an upper sun pillar (similar to a subsun, but extending above the sun instead of below it). Like all halos, these phenomena are caused by the reflection and/or refraction of sunlight by ice crystals suspended in the atmosphere, often in the form of cirrus or cirrostratus cl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Novaya Zemlya Effect
The Novaya Zemlya effect is a polar mirage caused by high refraction of sunlight between atmospheric thermal layers. The effect gives the impression that the sun is rising earlier than it actually should, and depending on the meteorological situation, the effect will present the Sun as a line or a square — sometimes referred to as the rectangular sun — made up of flattened hourglass shapes. The mirage requires rays of sunlight to travel through an inversion layer for hundreds of kilometres, and depends on the inversion layer's temperature gradient. The sunlight must bend to the Earth's curvature at least to allow an elevation rise of 5° for sight of the solar disk. The first person to record the phenomenon was Gerrit de Veer, a member of Willem Barentsz's ill-fated third expedition into the north polar region in 1596–1597. Trapped by the ice, the party was forced to stay for the winter in a makeshift lodge on the archipelago of Novaya Zemlya and endure the polar night. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subsun
A subsun (also spelled sub-sun) is an optical phenomenon that appears as a glowing spot visible within clouds or mist when observed from above. The subsun appears directly below the actual Sun, and is caused by sunlight reflecting off of numerous tiny ice crystals suspended in the atmosphere. As such, the effect belongs to the family of halos. The region of ice crystals acts as a large mirror, creating a virtual image of the Sun appearing below the horizon, analogous to the Sun's reflection in a body of water. The ice crystals responsible for a subsun are typically in the shape of flat hexagonal plates. As they fall through the air, their aerodynamic properties cause them to orient themselves horizontally, i.e., with their hexagonal surfaces parallel to the Earth's surface. When they are disturbed by turbulence, however, the plates start to "wobble", causing their surfaces to deviate some degrees from the ideal horizontal orientation, and causing the reflection (i.e., the s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Light Pillar
A light pillar is an atmospheric optical phenomenon in which a vertical beam of light appears to extend above and/or below a light source. The effect is created by the reflection of light from tiny ice crystals that are suspended in the atmosphere or that comprise high-altitude clouds (e.g. cirrostratus or cirrus clouds).Colonne lumineuse by the . If the light comes from the Sun (usually when it is near or even below the horizon), the phenomenon is called a sun pillar or sola ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lower Tangent Arc
Tangent arcs are a type of halo, an atmospheric optical phenomenon, which appears above and below the observed Sun or Moon, tangent to the 22° halo. To produce these arcs, rod-shaped hexagonal ice crystals need to have their long axis aligned horizontally. Description Upper arc The shape of an upper tangent arc varies with the elevation of the Sun; while the Sun is low (less than 29–32°) it appears as an arc over the observed Sun forming a sharp angle. As the Sun is seen to rise above the Earth's horizon, the curved wings of the arc lower towards the 22° halo while gradually becoming longer. As the Sun rises over 29–32°, the upper tangent arc unites with the lower tangent arc to form the circumscribed halo. Lower arc The lower tangent arc is rarely observable, appearing under and tangent to a 22° halo centred on the Sun. Just like upper tangent arcs, the shape of a lower arc is dependent on the altitude of the Sun. As the Sun is observed slipping over Earth' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
