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Refraction at interface. Many materials have a well-characterized refractive index, but these indices often depend strongly upon the frequency of light, causing optical dispersion. Standard refractive index measurements are taken at the "yellow doublet" sodium D line, with a wavelength (λ) of 589 nanometers.
Refraction of light at the interface between two media of different refractive indices, with n 2 > n 1.Since the phase velocity is lower in the second medium (v 2 < v 1), the angle of refraction θ 2 is less than the angle of incidence θ 1; that is, the ray in the higher-index medium is closer to the normal.
Young [6] [11] distinguished several regions where different methods for calculating astronomical refraction were applicable. In the upper portion of the sky, with a zenith distance of less than 70° (or an altitude over 20°), various simple refraction formulas based on the index of refraction (and hence on the temperature, pressure, and humidity) at the observer are adequate.
Light rays coming from the zenith take the shortest-possible path (1 ⁄ 38) through the air mass, yielding less scattering. Light rays coming from the horizon take the longest-possible path through the air, yielding more scattering. [11] The blueness is at the horizon because the blue light coming from great distances is also preferentially ...
The 46° halo was first explained as being caused by refractions through ice crystals in 1679 by the French physicist Edmé Mariotte (1620–1684) in terms of light refraction [1] Jacobowitz in 1971 was the first to apply the ray-tracing technique to hexagonal ice crystal. Wendling et al. (1979) extended Jacobowitz's work from hexagonal ice ...
The ordinary law of refraction was at that time attributed to René Descartes (d. 1650), who had tried to explain it by supposing that light was a force that propagated instantaneously, or that light was analogous to a tennis ball that traveled faster in the denser medium, [44] [45] either premise being inconsistent with Fermat's.
6. Vintage World Maps. Wikipedia Commons/Public Domain. A 17th-century world map by Joan Blaeu, like his “Nova Totius Terrarum Orbis Tabula,” can command prices that soar into the thousands.
Absorption of light in water. The refractive index of water at 20 °C for visible light is 1.33. [1] The refractive index of normal ice is 1.31 (from List of refractive indices). In general, an index of refraction is a complex number with real and imaginary parts, where the latter indicates the strength of absorption loss at a particular ...