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SRML Glossary "C"
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
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The process
of comparing an instrument's output signal with reality. Instruments that
measure solar energy tend to "drift", that is, their output signals do not
mean the same thing from one time period to another. Because of this, they
are periodically (annually or semi-annually) re-calibrated against more
reliable instruments. Figure 1 in Solar Radiation Research Laboratory (SRRL) Final Report: Fiscal Years 2019-2021
illustrates the Solar Radiation Research Laboratory where calibrations are conducted.
Figure 3 shows radiometers on a calibration table that are calibrated to a reference
instrument traceable to the World Radiometric Reference (WRR).
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(cal) The
amount of energy required to raise the temperature of one gram of water
one degree Celsius at 50°C, or 4.1855 joules.
Note that the large calorie (Cal) is the amount of energy required to raise
one kilogram of water one degree Celsius; that is, 1 Cal =
1000 cal. To confuse matters, dietary Calories are almost never capitalized
as they should be, and are often mistaken for calories.
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An instrument that measures heat.
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A clear
glass sphere that focuses the sun's rays onto a special strip chart, producing
a charred path when there is bright sunshine.
The length of the path determines the bright sunshine
duration. 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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The metric
temperature scale for which 0°C is the temperature at which water freezes
and 100°C is the temperature at which water boils, at standard atmospheric
pressure. The conversion from Farenheit
to Celsius is
C = ( F - 32 ) / 1.8
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A solar
power generator which uses a series of tracking mirrors ( heliostats)
or a paraboloid (3-dimensional parabola, or dish) of mirrors to focus solar
energy onto a single central receiver such as a boiler, engine, or
photovoltaic array.
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The amount
of solar radiation coming from a circle in the sky centered on the sun's
disk and having a radius of between 2.5 and 3.5 degrees, depending on the
type of instrument being used to measure beam
radiation (direct normal irradiance). The Best Practices Handbook for the Collection and Use of Solar Resource Data for Solar Energy Applications: Third Edition has a fuller discussion.
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The typical
or expected (average) weather pattern, as opposed to the actual weather
at any given instant.
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The fraction of the sky dome covered by clouds. This fraction is typically expressed either
as tenths (1/10, ..., 10/10) or eighths (1/8, ..., 8/8).
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The fraction of the sky dome covered by clouds. This fraction is typically expressed either
as tenths (1/10, ..., 10/10) or eighths (1/8, ..., 8/8). Some researchers refer to this as
cloud amount, to clarify the distinction from cloud type, which
is the nature of the cloud cover.
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The type of clouds (e.g., altostratus, cumulonimbus) that form each layer of the sky dome.
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Climate Monitoring and Diagnostics Laboratory,
One of several research laboratories forming the Environmental Research Laboratories
within the
National Oceanic and Atmospheric Administration
(under the U.S. Departmentof Commerce).
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A device that receives solar energy and converts it to useful energy forms. The following
figure from
Solar Radiation Data Manual for Flat-Plate and Concentrating Collectors illustrates several types of collectors.
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The working
fluid in a collector that uses the heat of
solar energy. These collectors focus the sun's rays on central containers
or tubes that contain a fluid that is heated and then used to heat air or
water, or to power motors or turbines.
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A system that tracks the path of the sun by pivoting on one axis (typically East-West or
North-South), using shiny parabolic troughs to heat the collector fluid that passes through
a tube at the focus. Below is an illustration from the
Solar Radiation Data Manual for Flat Plate and Concentrating
Collectors.
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A collector
that enhances solar energy by focusing it onto a smaller area through mirrored
surfaces or lenses.
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The amount of air-conditioning needed, created by adding up all temperature differences of
the form ( daily temperature in °F - 65°F ) for each day in which the temperature
exceeds 65°F.
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The effects
of radiance incidence angle on pyranometer
measurement performance. If a pyranometer is rotated while a beam of light
is shined upon it, it will record the maximum energy when it is directly
facing the beam, and the energy will fall to zero when it is sideways to
(or facing away from) the beam. A graph of the energy reported by the pyranometer
as the angle it makes with the beam of light should look like the cosine
of the angle, if the instrument were perfect. Pyranometers have imperfections
that keep them from producing this curve (see graph below for an example).
Click here for graph
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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 25, 2022.
Home page URL: solardata.uoregon.edu |