To use all functions of this page, please activate cookies in your browser.
my.chemeurope.com
With an accout for my.chemeurope.com you can always see everything at a glance – and you can configure your own website and individual newsletter.
- My watch list
- My saved searches
- My saved topics
- My newsletter
Pyrgeometer
A pyrgeometer is a device that measures the atmospheric infra-red radiation spectrum that extends approximately from 4.5 µm to 100 µm.
Additional recommended knowledge
Pyrgeometer components
A pyrgeometer consists of the following major components:
Measurement of long wave downward radiationThe atmosphere and the pyrgeometer (in effect the earth surface) exchange long wave IR radiation. This results in a net radiation balance according to:
Where:
The pyrgeometer's thermopile detects the net radiation balance between the incoming and outgoing long wave radiation flux and converts it to a voltage according to the equation below.
Where:
The value for S is determined during calibration of the instrument. The calibration is performed at the production factory with a reference instrument traceable to a regional calibration center.[1] To derive the absolute downward long wave flux, the temperature of the pyrgeometer has to be taken into account. It is measured using a temperature sensor inside the instrument, near the cold junctions of the thermopile. The pyrgeometer is considered to approximate a black body. Due to this it emits long wave radiation according to:
From the calculations above the incoming long wave radiation can be derived. This is usually done by rearranging the equations above to yield the so called pyrgeometer equation by Albrecht and Cox. Where all the variables have the same meaning as before. As a result, the detected voltage and instrument temperature yield the total global long wave downward radiation. UsagePyrgeometers are frequently used in meteorology, climatology studies. The atmospheric long-wave downward radiation is of interest for research into long term climate changes. The signals are generally detected using a data logging system, capable of taking high resolution samples in the millivolt range.
References
See also
Categories: Electromagnetic radiation meters | Radiometry |
|||
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Pyrgeometer". A list of authors is available in Wikipedia. |