Aerosol Optical Depth (AOD) at 830 nm measured with the same LED sun photometer from 1990 to 2016 at Geronimo Creek Observatory, Texas. Measurements made at or near solar noon when the Sun is not obstructed by clouds. Peaks indicate smoke, dust and smog. Saharan dust events are measured each summer.
In physics, optical depth or optical thickness is the natural logarithm of the ratio of incident to transmitted radiant power through a material.
Thus, the larger the optical depth, the smaller the amount of transmitted radiant power through the material.
Spectral optical depth or spectral optical thickness is the natural logarithm of the ratio of incident to transmitted spectral radiant power through a material.[1] Optical depth is dimensionless, and in particular is not a length, though it is a monotonically increasing function of optical path length, and approaches zero as the path length approaches zero. The use of the term "optical density" for optical depth is discouraged.[1]
In chemistry, a closely related quantity called "absorbance" or "decadic absorbance" is used instead of optical depth: the common logarithm of the ratio of incident to transmitted radiant power through a material. It is the optical depth divided by loge(10), because of the different logarithm bases used.
^ abIUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "Absorbance". doi:10.1351/goldbook.A00028
In physics, opticaldepth or optical thickness is the natural logarithm of the ratio of incident to transmitted radiant power through a material. Thus...
1–2 km—and has the equivalent opticaldepth 0.1–0.2 km at the wavelength 2.2 μm. The normal opticaldepth is 0.1–0.2. The opticaldepth of the λ ring shows strong...
Rosseland opticaldepth An extinction coefficient of an atmosphere, which describes the net opacity to radiation at a given depth. See opticaldepth. rotation...
In optics, optical path length (OPL, denoted Λ in equations), also known as optical length or optical distance, is the length that light needs to travel...
modulated by the opticaldepth to the viewer (i.e. 1/e times the emission at 1 opticaldepth, 1/e2 times the emission at 2 optical depths, etc.). Near...
proportion of dust in the rings (between 20% and 70%) is high, while their opticaldepth is low to moderate, at less than 0.1. Uniquely, the Adams ring includes...
MOLA Digital Elevation Map (DEM) were used to calculate atmospheric opticaldepth (AOD) over northern and southern walls of Valles Marineris. On northern...
opticaldepth is proportional to the number of absorbers and scatterers along that length, typically increasing with decreasing altitude. The optical...
related to opticaldepth by A = τ ln 10 = τ log 10 e , {\displaystyle A={\frac {\tau }{\ln 10}}=\tau \log _{10}e\,,} where τ is the opticaldepth. Spectral...
related to Optical illusion. Optical Illusion Examples by Great Optical Illusions Optical Illusions & Visual Phenomena by Michael Bach Optical Illusions...
around 15 μm. The power law mentioned above allows estimation of the opticaldepth τ {\displaystyle \scriptstyle \tau } of the main ring: τ l = 4.7 × 10...
Earlier Voyager observations of density waves in the A and B rings and an opticaldepth profile had yielded a mass of about 0.75 Mimas masses, with later observations...
measurements. These include measuring the ozone layer, haze (aerosol opticaldepth), and the total column water vapor. The project began in May 1988, when...
temperatures evaporating water into the atmosphere, increasing its opticaldepth. This positive feedback means the planet cannot cool down through longwave...
the plasma becomes opaque, equivalent to an opticaldepth of approximately 2⁄3, or equivalently, a depth from which 50% of light will escape without being...
in a line toward the observer. Another name for this phenomenon is depth from optical expansion. The dynamic stimulus change enables the observer not only...
it ranges from 56% to 73% depending on the minimum opticaldepth considered (lower when opticaldepth is large, and higher when it is low, such that subvisible...
optically thin. Starlight traveling through a kiloparsec column undergoes about a magnitude of extinction, so that the opticaldepth ~ 1. An optical depth...
shapes, making it difficult to determine their evolving atmospheric opticaldepth value. The conditions present during the creation of the soot are believed...
Penetration depth is a measure of how deep light or any electromagnetic radiation can penetrate into a material. It is defined as the depth at which the...
is related to opticaldepth and to absorbance as T = e − τ = 10 − A , {\displaystyle T=e^{-\tau }=10^{-A},} where τ is the opticaldepth; A is the absorbance...
defined as the radius to the layer in the Sun's photosphere where the opticaldepth equals 2/3: 1 R ⊙ = 6.957 × 10 8 m {\displaystyle 1\,R_{\odot }=6.957\times...
Mars. Orbiter measurements suggest that the globally-averaged dust opticaldepth has a background level of 0.15 and peaks in the perihelion season (southern...
In visual perception, an optical illusion (also called a visual illusion) is an illusion caused by the visual system and characterized by a visual percept...
Optical coherence tomography (OCT) is an imaging technique that uses interferometry with short-coherence-length light to obtain micrometer-level depth...
different paths through the atmosphere and so determine the difference in opticaldepth between the two columns (Alternative a solar atlas can be employed,...
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