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Glossary of Solar Radiation Resource Terms |
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Other relevant glossaries
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Temporal -
pertaining to time, such as temporal variation (variation over time).
Terrestrial Radiation -
electromagnetic radiation that
is emitted by the Earth, as opposed to solar radiation
emitted by the sun.
Thermopile -
a set of thermocouple junctions connected in series in order to boost the voltage to a meaningful
amount (usually measured in millivolts). A thermocouple is a metallic strip or wire that
produces an electromagnetic potential (voltage) when the two ends (junctions) are at different
temperatures. The "cold" junctions of thermopile radiometers are painted white to reflect radiation,
and the "hot" junctions are painted black to absorb radiation.
TMY -
Typical Meteorological Year, a "typical" year of hourly solar
and meteorological values which is designed to produce the expected climate of a location throughout
a year.
Total Solar Radiation -
solar radiation that is the sum of
direct,
diffuse, and
ground-reflected radiation;
however, because ground reflected radiation is usually insignificant compared to direct
and diffuse, for all practical purposes global radiation is said to be the sum of direct
and diffuse radiation only.
Click Shining On (Figure 3) to see solar components
Tracking Collector -
any collector that changes its orientation throughout the day in order to
follow the path of the sun in the sky. Two-axis trackers continually face the sun, while
one-axis trackers rotate on one axis so that collectors receive the
maximum amount of circumsolar radiation
that strikes the axis.
Transient Response -
the short-term response of an instrument caused by a change of status of the instrument's
environment. For example, the switching of a power supply on and off will send very short-term
power spikes that can be detected by a volt meter with sufficiently rapid response time.
Transmittance -
the fraction or percent of a particular frequency or wavelength of
electromagnetic radiation that passes
through a substance without being absorbed or reflected.
Transpiration -
the transfer of water from the leaves of plants to
water vapor in the atmosphere.
TRNSYS -
TRNSYS is computer
software that is used for designing buildings and systems that utilize solar energy.
Troposphere -
the lowest region of the atmosphere between the surface of the earth and the stratosphere.
In the troposphere the temperature usually decreases with increasing altitude.
Trough -
a colloquial and descriptive name of the parabolic cylinder (surface of constant parabolic
cross-section) used for collecting solar radiation along the focal length.
Trough systems follow 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 .
Turbidity -
a measure of the opacity of the atmosphere. A perfectly clear sky has a turbidity of 0, and a
perfectly opaque sky has a turbidity of 1. Turbidity is affected by air molecules and
aerosols.
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