Photo-synthetically active radiation in the spectral range 400-700 nm. It is an essential factor for plant growth
(Forming of chlorophyll).
(PAR = Photo-synthetically Active Radiation)


Instrument for the measurement of the short-wave. The sensor consists of thermo-elements. The acquired spectral range is approx. between 300 and 2800 nm.


Instrument for the measurement of the radiation balance in the total spectrum (short- and long-wave range) of the solar radiation 300 - > 60 000 nm.
Two separate thermo-elements acquire the infalling and reflected radiation and output them as electric voltage. The reference temperature is measured by a Pt100.

Radiation Balance

Difference from infalling global radiation and the reflected radiation of the ground.

Radiation Balance Meter

Two contra-connected thermopiles form a difference: the global radiation infalling from above, and the radiation of the ground reflected from below. The difference is the radiation balance and is output as electric voltage.

Radiation Intensity

Radiation flux density (W/m2).

Silicon Photodiode

Semi-conductor diodes, converting visible light, or IR-, UV as well, into electric power.

Silicon Pyranometer

The sensor-element of this instrument is a special silicon-photodiode. The acquired spectral range is approx. between 350 and 1000 nm.

Solar Constant

Radiation power of the solar radiation out of atmosphere.
Mean value determined by WMO : 1367 W/m2.

Solar Radiation

The solar radiation is the radiation of the sun. The maximum power of the electro-magnetic radiation is the visible light, however, comprises also other electro-magnetic waves from X-rays and UV-radiation up to radio waves.

Sunshine Duration

Time period of the direct solar radiation in a certain place.


Consisting of blackened area and thermo-elements, which are affiliated with each others. Radiation is converted into heat and is output as thermo-voltage.


1 cal cm-2 min-1 = 697.8 Wm-2
1 Wm-2 = 0.001433 cal cm-2 min-1
1 cal cm-2 d-1 = 0.0116 kWh m-2

UV Radiation

Ultra-violet radiation, below the visible radiation.
The ultra-violet spectrum comprises wave-lengths from 1 nm to 380 nm.

UV-A Radiation

Radiation in the spectral range 380-315 nm.
It is essential for the strengthening of the human immunity system, and is responsible for the sun tan of the skin.

UV-B Radiation

Radiation in the spectral range 280-315 nm.
It is dangerous for irreversible damages of the human skin (cancer of the skin).

Visible Radiation

The light perceived by the human eye in the spectral range 360 ... 780 nm.


World Meteorological Organization.



Adolf Thies GmbH & Co. KG Hauptstraße 76 37083 Göttingen Germany Phone +49 551 / 79001-0 Fax +49 551 / 79001-65
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