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Glossary of Solar Radiation Resource Terms |
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Other relevant glossaries
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Radiation -
in the context of the RReDC, synonymous with
electromagnetic radiation,
or the energy produced by an oscillating electrical (and magnetic) field, transmitted by
photons. See
Electromagnetic Spectrum.
Radiometer -
an instrument that measures radiance, or the
radiation emitted by an object.
Radiosonde -
an instrument package that moves through the atmosphere, usually attached to a
balloon, and transmits data over a radio frequency.
Raman Scattering -
Sir Chandrasekhara Venkata Raman (1888-1970) was the Indian physicist who
discovered that when a beam of light passes through a liquid or a gas, it
is scattered and the frequency of some of the scattered light is changed.
The amount of change is a function of the scattering particles and the
wavelengths of light.
Random Error -
the difference between the actual and the desired quantity that varies randomly; that is, if
a probability distribution of differences is produced, it is the Gaussian error function.
Rayleigh Scattering -
the scattering of solar radiation by (mathematically spherical) particles in the
atmosphere which are much smaller than the wavelength of light, analyzed by Lord Rayleigh.
Rayleigh scattering explains the blue sky.
RCC -
Radiometer Calibration & Characterization (RCC) software is used to
automate the
BORCAL process.
The RCC controls all data acquisition from the reference
radiometers and those under calbration,
displays several color-coded fields representing the present sky condition and instrument performance,
builds an instrument calibration database, and generates the final calibration report.
Renewable Energy -
there is no formal definition for this term. Typical usage defines it as any
energy source that is replenished at least as fast as it is used. Standard examples are
solar, wind, hydroelectric, and biomass products.
Receiver -
a device that receives solar energy and converts it to useful energy forms. The following
figure from
Shining On illustrates several types of receivers.
Reflectance -
the fraction or percent of a particular frequency or wavelength of
electromagnetic radiation that is reflected
from the surface of a substance without being absorbed or transmitted.
Refraction -
the bending of electromagnetic radiation
by its passage through a medium of a high refractive index.
Light is refracted by passing through a lens, water, or the
atmosphere.
Relative Humidity -
the amount of water vapor in the air expressed as the
ratio between the measured amount and the maximum possible amount (the saturation point at
which water condenses as dew).
Remote Sensing -
the determination of a quantity by detecting it from a distance. A common application of remote
sensing is the use of satellite-borne instruments to determine the location and amount of
resources on the surface of the Earth.
Re-radiation -
the re-emission of electromagnetic radiation that
had been previously absorbed by a substance.
Rotating Shadow Band Radiometer -
an instrument that determines
total solar radiation and
diffuse sky radiation by
periodically shading the total sky sensor from the sun with a rotating
shadow band.
Below is a picture of a rotating shadow band radiometer at the
Solar Radiation Research Laboratory. The curved black shadowband at
the right of the instrument is at rest; once every minute, it rotates 180° to obscure the sun for
a few seconds, then returns to its resting position.
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