Opacity is a term used in optics, atmospheric physics and astrophysics to quantify how materials absorb light. The opacity is a function of the composition, density, and temperature of a given absorbing medium.
opacity A quantity that measures a material's ability to block electromagnetic radiation. Opacity is the opposite of transparency.
Opacity
(a) A measure of the resistance of a medium to the transmission of visible light or other forms of radiation. A material that is opaque is said to have a high opacity; one that is transparent has low opacity.
Opacity: It takes a LONG time for photons produced by nuclear reactions in the core to reach the surface. In the opaque interior a photon travels only about 1 centimeter before it runs into an atom or ion and is absorbed.
Opacity broadening: Electromagnetic radiation emitted at a particular point in space can be absorbed as it travels through space. This absorption depends on wavelength.
opacity
A property of matter that prevents light from passing through it; non-transparent. The opacity or opaqueness of something depends on the frequency of the light.
Opacity
The resistance of a gas to the passage of radiation.
Open (Escape) Orbit ...
Opacity - The ability of a substance to absorb radiation. The higher the opacity, the less transparent the substance is
Opposition - The configuration of a planet or other body when it appears opposite the Sun in the sky ...
Opacity
The degree to which light is prevented from passing through an object or a substance. Opacity is the opposite of transparency. As an object's opacity increases, the amount of light passing through it decreases.
Opacity of the Earth's atmosphere
See also
*Atmospheric window
*Astronomical window
*Optical window ...
Opacity taken from the tables derived by G. Keller and R. Meyerott for assumed mixtures of hydrogen, helium, and heavy elements ranging from X = 99%, Y = 1%, Z = 0 to X = 0, Y = 50%, Z = 50%. [H76]
kelvin ...
opacity - Absorbing power; capacity to impede the passage of light.
optics - The branch of physics that deals with light and its properties.
parallax - An apparent displacement of an object due to a motion of the observer.
opacity - (n.)
The lack of complete transparency of a gas.
open cluster - (n.) ...
Opacity: The property of a substance that determines how hard it is for radiation to get through that substance (hence how "opaque" that substance is). The atmosphere has low opacity to light.
The opacity of Earth's atmosphere"the extent to which it absorbs radiation"varies greatly with wavelength. Only radio waves, some infrared wavelengths, and visible light can penetrate the atmosphere and reach the ground from space.
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281. Opacity
The resistance of a gas to the passage of radiation.
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282. Open (Escape) Orbit
An orbit which leads away from the central body, never to return.
Jasper is an Opacity , impure variety of silica, usually red, yellow or brown in color. This mineral breaks with a smooth surface, and is used for ornamentation or as a gemstone....
. The mirror signifies the wisdom of God as a hidden mystery.
photographic transmission density The common logarithm of opacity. Hence, film transmitting 100 percent of the light has a density of zero, transmitting 10 percent, a density of 1, etc. Density may be diffuse, specular, or intermediate.
This "resistance" to the free travel of photons through the gas is called opacity, as in opaque. The higher the opacity of the material, the harder it is for light to move through it.
The origin of the difference is the higher opacity of the stellar gas in the part of the spectrum where the star absorbs the radiation, showing that "radii" for stars this large and cool are inherently uncertain.
Our understanding of the universe back to very early times suggests that there was a past horizon, though in practice our view is limited by the opacity of the universe at early times.
A flurry of work from various directions in the 1990s addressed this whole issue of the optical opacity of disk galaxies (as described in the proceedings of the Cardiff workshop The Opacity of Galaxy Disks.
By increasing the opacity of the star's atmosphere, light radiating outwards from the hotter, inner regions of the star is absorbed, and only light coming from the outer, cooler layers of the star escapes.
The temperatures of the Cepheids are in the 6000-8000K range, which is when hydrogen atoms become ionized, and this causes the opacity of the atmosphere to change.
"The major surprise was the opacity of the plume the impactor created and the light it gave off," said Deep Impact Principal Investigator Dr. Michael A'Hearn of the University of Maryland, College Park.
Radiation is easily absorbed by H-, and so the outer layers will have a high opacity.
The graph below shows the opacity of our atmosphere to EM waves in different frequencies. We can see that the Earth's atmosphere is opaque to, say, gamma rays and transparent to the visible light. So, we have to put gamma ray telescopes in space.
days to global obscuration of the surface, and measurements at the Viking lander sites indicate that atmospheric transmission can be reduced by a factor of more than 20. The intensification process is evidently short-lived, as atmospheric opacity ...
1939 - Rupert Wildt realizes the importance of the negative hydrogen ion for stellar opacity
1952 - Walter Baade distinguishes between Cepheid I and Cepheid II variable stars ...
The continuum opacity of the sun is provided by bound-free and free-free transitions of the hydrogen ion . This was proposed by R. Wildt in 1940, and shown to be quantum mechanically consistent with observations by Chandrasekhar in 1945.
RIOMETER (Relative Ionospheric Opacity meter). A specially designed radio receiver for continuous monitoring of cosmic noise. The absorption of cosmic noise in the polar regions is very sensitive to the solar low-energy cosmic ray flux.
 See also: Light, Temperature, Time, Energy, Earth
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