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  2. Atmospheric refraction - Wikipedia

    en.wikipedia.org/wiki/Atmospheric_refraction

    Diagram showing displacement of the Sun's image at sunrise and sunset Comparison of inferior and superior mirages due to differing air refractive indices, n. Atmospheric refraction is the deviation of light or other electromagnetic wave from a straight line as it passes through the atmosphere due to the variation in air density as a function of height. [1]

  3. Image gradient - Wikipedia

    en.wikipedia.org/wiki/Image_gradient

    Two types of gradients, with blue arrows to indicate the direction of the gradient. Light areas indicate higher pixel values A blue and green color gradient. An image gradient is a directional change in the intensity or color in an image. The gradient of the image is one of the fundamental building blocks in image processing.

  4. Atmospheric optics - Wikipedia

    en.wikipedia.org/wiki/Atmospheric_optics

    In these three frames, the superior mirage evolves from a 3-image mirage to a 5-image mirage, and back to a 2-image mirage. Such a display is consistent with a Fata Morgana . A mirage is a naturally occurring optical phenomenon in which light rays are bent to produce a displaced image of distant objects or the sky.

  5. Belt of Venus - Wikipedia

    en.wikipedia.org/wiki/Belt_of_Venus

    The Belt of Venus – also called Venus's Girdle, the antitwilight arch, or antitwilight [1] – is an atmospheric phenomenon visible shortly before sunrise or after sunset, during civil twilight. It is a pinkish glow that surrounds the observer, extending roughly 10–20° above the horizon .

  6. Green flash - Wikipedia

    en.wikipedia.org/wiki/Green_flash

    (Of course, a magnified image might be projected onto a sheet of paper for safe viewing.) As the Sun gets closer to the horizon, the green rim becomes fainter due to atmospheric reddening. [ 10 ] According to the above, it is probably correct to conclude that although a green rim is present during every sunset, a green flash is rarer because of ...

  7. Mirage - Wikipedia

    en.wikipedia.org/wiki/Mirage

    A superior mirage is one in which the mirage image appears to be located above the real object. A superior mirage occurs when the air below the line of sight is colder than the air above it. This unusual arrangement is called a temperature inversion. During the daytime, the normal temperature gradient of the atmosphere is cold air above warm air.

  8. Mirage of astronomical objects - Wikipedia

    en.wikipedia.org/wiki/Mirage_of_astronomical_objects

    Due to a normal atmospheric refraction, sunrise occurs shortly before the Sun crosses above the horizon. Light from the Sun is bent, or refracted, as it enters Earth's atmosphere. This effect causes the apparent sunrise to be earlier than the actual sunrise. Similarly, apparent sunset occurs slightly later than actual sunset.

  9. Aerial perspective - Wikipedia

    en.wikipedia.org/wiki/Aerial_perspective

    In this picture, the aerial perspective effect is emphasized by a range of mountains at different distances, photographed in a nearly contre-jour condition.. Aerial perspective, or atmospheric perspective, refers to the effect the atmosphere has on the appearance of an object as viewed from a distance.