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SRML Glossary — "E" Special thanks to NREL We'd like to thank the National Renewable Energy Laboratory for making available to us their glossary, which is the basis of ours. We've edited and reformatted it, and linked it to our Web pages, and we'll continue to add our own specialized terms, illustrations, and examples. Please note that the Solar Radiation Monitoring Laboratory takes full responsibility for any inaccuracies that may occur. Links to other glossary sections: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
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| Earth Sun Distance Factor | The
distance between the earth and the sun changes by +/-1.5% from average as
the earth orbits the sun. The aphelion of the orbit occurs approximately
July 5 and the perihelion occurs about January 3-5. The intensity of radiation
falls off by the inverse square of the distance from the source. The earth-sun
distance factor is the amount that the extraterrestrial irradiance changes
as the earth orbits the sun
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The energy
produced by an oscillating electrical (and magnetic) field, transmitted
by photons. See Electromagnetic
Spectrum. |
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The entire
energy range of electromagnetic
radiation specified by frequency, wavelength, or photon energy. The
low end of the spectrum is infrared radiation
(heat), and passes through the colors of visual light
from red through violet, through ultraviolet
radiation, x-rays, and gamma rays. Radio and television are transmitted
on specific electromagnetic frequencies. |
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The ratio
of the actual amount of electromagnetic
radiation emitted by an object to the amount emitted by an ideal blackbody
at the same temperature. |
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the ability
to do work. Some Units of energy, such as foot-pounds, measure the ability
to lift a weight a certain height, units, such as calorie,
indicate the ability to increase temperature, while units of radiation
are usually the frequencies or wavelengths of photons.
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Environment
Canada is the federal coordinating agency for all environmental issues
pertaining to Canada. |
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The Electric
Power Research Institute, a research consortium of electric power companies
in the United States. |
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The annual
East-West swing of the location of the Sun which can be detected by noting
the position of the Sun at the same time (such as noon) each day. This motion
is caused by the libration (wobble) of the Earth and can be estimated by
(Spencer, J. W. (1971). Fourier series representation of the position
of the Sun. Search 2 (5), 172 ) :
ET = 229.18 * ( 0.000075 + 0.001868 cos D - 0.032077 sin D -0.014615 cos 2D - 0.040849 sin 2D ) where D = nD ( 360° / 365 ) and nD is the number of the day (e.g., Feb. 1 makes nD = 32). NREL uses solar position algorithms that do not require the equation of time (Michalsky, J. J. (1988). The Astronomical Almanac's algorithm for approximate solar position (1950-2050). Solar Energy 40 (3), 227-235 ) . |
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Literally
"equal night", a day when the number of hours of daylight equals the number
of hours of night. The vernal equinox, usually March 21, signals the onset
of Spring, while the autumnal equinox, usually September 21, signals the
onset of Autumn. |
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A metric
unit of energy (dyne-cm). A joule is 100,000
ergs. |
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Literally
"inferior substitute", the 222 measurement sites in the 1952-1975 SOLMET/ERSATZ
solar & meteorological hourly network that did not measure solar radiation.
The solar radiation for these sites was modeled from cloud cover data and
other information. The SOLMET/ERSATZ network has been replaced by the newer
National Solar Radiation
Data Base. |
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Extraterrestrial
radiation, also known as "top-of-atmosphere" (TOA) irradiance, is the amount
of global horizontal radiation
that a location on Earth would receive if there was no atmosphere or clouds
(i.e., in outer space). This number is used as the reference amount against
which actual solar energy measurements are compared. |
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The process
of converting a substance (such as water) from its liquid phase to its gaseous
phase. |
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Abbreviated
ETR, also known as "top-of-atmosphere" (TOA) irradiance, is the amount of
global horizontal radiation
that a location on Earth would receive if there was no atmosphere or clouds
(i.e., in outer space). This number is used as the reference amount against
which actual solar energy measurements are compared.
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| Links to other glossary sections: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z  © 2022, UO Solar Radiation Monitoring Laboratory. Last revised:
March 29, 2022.
Home page URL: solardata.uoregon.edu |
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