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Rayleigh scattering causes the blue color of the daytime sky and the reddening of the Sun at sunset. Rayleigh scattering (/ ˈ r eɪ l i / RAY-lee) is the scattering or deflection of light, or other electromagnetic radiation, by particles with a size much smaller than the wavelength of the radiation.
The Rayleigh sky model describes the observed polarization pattern of the daytime sky. Within the atmosphere, Rayleigh scattering of light by air molecules, water, dust, and aerosols causes the sky's light to have a defined polarization pattern. The same elastic scattering processes cause the sky to be blue.
The scattering curve shown is calculated for sunlight passing vertically through the atmosphere and is based on Bucholtz, Anthony (1995). "Rayleigh-scattering calculations for the terrestrial atmosphere". Applied Optics 34 (15). Other details, such as scattering from dust and absorption of some light by greenhouse gases are not shown.
SI prefixes are used with the rayleigh. One rayleigh (1 R) is defined as a column emission rate of 10 10 photons per square metre per column per second. A column is one centimeter cross-section [clarify]. [3] The rayleigh is a unit of an apparent emission rate, without allowances being made for scattering or absorption.
Scattering and absorption are major causes of the attenuation of sunlight radiation by the atmosphere. Scattering varies as a function of the ratio of particle diameters (of particulates in the atmosphere) to the wavelength of the incident radiation. When this ratio is less than about one-tenth, Rayleigh scattering occurs. (In this case, the ...
Rayleigh scattering regime is the scattering of light, or other electromagnetic radiation, by particles much smaller than the wavelength of the light. Rayleigh scattering can be defined as scattering in small size parameter regime x ≪ 1 {\displaystyle x\ll 1} .
This means that each photon emitted at the photosphere suffers an average of less than one scattering before it reaches the observer. At the temperature at optical depth 2/3, the energy emitted by the star (the original derivation is for the Sun) matches the observed total energy emitted. [citation needed] [clarification needed]
There are three main sources of attenuation (Hayes & Latham 1975): Rayleigh scattering by air molecules, Mie scattering by aerosols, and molecular absorption (primarily by ozone). The relative contribution of each source varies with elevation above sea level, and the concentrations of aerosols and ozone cannot be derived simply from hydrostatic ...