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SRML Glossary — "B" 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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An instrument that measures atmospheric pressure.
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The pressure (force per area) created by the weight of the atmosphere, measured by
a barometer. At higher elevations, the atmospheric pressure is lower because there
is less air.
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| Synonym
for direct normal irradiance,
the amount of solar radiation from the
direction of the sun. Click on
Best Practices Handbook
for the Collection and Use of Solar Resource Data for Solar Energy Applications:
Third Edition
and go to Figure 2.6 to see the componets that make up incident solar irradiance.
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An indication of the average deviation of the predicted, or true values,
from the measured values. Typically expressed as twice the mean bias error
(MBE):
where:
yi is the ith predicted, or true value
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| A term for
the amount of reflected radiation compared to the amount of incident radiation,
or albedo, of a surface. The surface is not
perfectly specular. That is, the reflected intensity is not at the
same angle with respect to the surface normal as the incoming rays, nor
are the two intensities necessarily equal (in crude terms, when light bounces
off the Earth, some of it is absorbed and the rest of it bounces "funny",
not as it would off a mirror).
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Plants, crops, and trees; converted by solar fuel technologies into
fuels and byproducts. See the Biomass Resource
Information Clearinghouse.
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| Named after
Dr. Richard Bird, a scientist at SERI ( NREL),
this physical model uses properties of the atmosphere such as albedo,
turbidity, and precipitable
water to determine the amount of solar
radiation striking the earth's surface from a cloudless sky.
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The theoretical "perfect" absorber of light at all wavelengths. As blackbodies heat up,
they emit a characteristic double-exponential light frequency (energy) curve,
which is imperfectly seen in nature. For example, Figure on page 2.1 from
Best Practices Handbook for
the Collection and Use of Solar Resource Data for Solar Energy Applications: Third Edition
below shows the irradiance outside the earth's atmosphere and radiation from an black body
object heated to 5800K. As the light passes through the atmostphere, light is scattered, absorbed, and reflected. This can be seen in Figure 3.2 in the handbook.
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The most sensitive thermometer known to science. Invented
in 1880 by astronomer Samuel P. Langley, the bolometer is used to measure
light from the faintest stars and the sun's heat rays. It consists of a
fine wire connected to an electric circuit. When radiation falls on the
wire, it becomes very slightly warmer. This increases the electrical
resistance of the wire. The difference in conductivity is proportional to
the incident irradiance.
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(Broadband Outdoor Radiometer CALibration)
A method of calibrating pyrheliometers and pyranometers based on the summation technique at the Solar Radiation Research Laboratory (SRRL). Up to three days of clear-sky solar irradiance measurements taken at 30-second intervals from sunrise to sunset are used to compute the individual radiometer responsivities. For pyrheliometer calibrations, the reference direct normal irradiance is measured with an electrically self-calibrating absolute cavity radiometer traceable to the World Radiometric Reference (WRR). The individual pyrheliometer responsivity is computed as the mean ratio of the signal from the pyrheliometer (microvolts DC) to the reference irradiance (Watts per square meter) for each of the 30-second data samples. Pyranometer responsivities are computed from the ratio of the signal from each pyranometer (microvolts DC) to the reference global horizontal irradiance determined by the direct normal irradiance (measured with an absolute cavity radiometer) and the simultaneous diffuse horizontal irradiance (measured by a reference pyranometer placed under a solar-tracking shading disk): Global Horizontal = Direct Normal x cos(Z) + Diffuse Horizontal where Z = Solar Zenith Angle at the time of measurement. The reference pyranometer is calibrated prior to use in a BORCAL event by means of the Shade Calibration Technique. | ||||
| When the
sun casts an obvious shadow or when a Campbell-Stokes
sunshine recorder is recording. The lower limit for bright sunshine
(based on a Campbell-Stokes recorder) is between 70 W/m2 (very
dry air) and 280 W/m2 (very humid air).
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| Theoretically
the solar radiation arriving at the
earth from all frequencies or wavelengths, in practice limited to the spectral
range of radiometers, typically from 300
nm to 3000 nm wavelength. Meteorologists refer to this band as short-wave
radiation.
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The worldwide Baseline Surface Radiation Network,
or the program that manages it.
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| British
Thermal Unit, the amount of energy required to raise one pound of water
one degree Farenheit at 60°F, equivalent to 1055 joules
or 252.1 calories.
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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 15, 2022.
Home page: solardata.uoregon.edu |
