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Atmospheric refraction of the light from a star is zero in the zenith, less than 1′ (one arc-minute) at 45° apparent altitude, and still only 5.3′ at 10° altitude; it quickly increases as altitude decreases, reaching 9.9′ at 5° altitude, 18.4′ at 2° altitude, and 35.4′ at the horizon; [4] all values are for 10 °C and 1013.25 hPa ...
Atmospheric refraction influences the apparent position of astronomical and terrestrial objects, usually causing them to appear higher than they actually are. For this reason navigators, astronomers, and surveyors observe positions when these effects are minimal.
Chatoyancy, cat's eye gems such as chrysoberyl cat's eye or aquamarine cat's eye; Chromatic polarization; Diffraction, the apparent bending and spreading of light waves when they meet an obstruction; Dispersion; Double refraction or birefringence of calcite and other minerals; Double-slit experiment; Electroluminescence; Evanescent wave
The Sun appeared to rise two weeks earlier than expected; the real Sun had still been below the horizon, but its light rays followed the curvature of Earth. This effect is often called a Novaya Zemlya mirage. For every 111.12 kilometres (69.05 mi) that light rays travel parallel to Earth's surface, the Sun will appear 1° higher on the horizon.
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
Looming of the Canadian coast as seen from Rochester, New York, on April 16, 1871. Looming is the most noticeable and most often observed of these refraction phenomena. It is an abnormally large refraction of the object that increases the apparent elevation of the distant objects and sometimes allows an observer to see objects that are located below the horizon under normal conditions.
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.
The geometric range of vision is limited by the curvature of the Earth and depends on the eye level and the height of the object being viewed. In geodesy , the atmospheric refraction must be taken into account when calculating geodetic visibility.