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(3) Measuring Radiation

Atmo II 57. Physics of the Atmosphere II. (3) Measuring Radiation. Atmo II 58. Measuring Radiation. Christoph Bichler. Atmo II 59. Measuring Radiation. Atmo II 60. Measuring Radiation. UF.

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(3) Measuring Radiation

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  1. Atmo II 57 Physics of the Atmosphere II (3) Measuring Radiation

  2. Atmo II 58 Measuring Radiation Christoph Bichler

  3. Atmo II 59 Measuring Radiation

  4. Atmo II 60 Measuring Radiation UF At state-of-the-art meteorological stations, equipped with a sun-tracker, solar radiation (irradiance) measure-ments comprise: Direct solar radiation (S), with a pyrheliometer Global solar radiation (G) with a pyranometer, Diffuse solar radiation (H) with a shadedpyranometer. G = S cosθ + H G H S

  5. Atmo II 61 Measuring Radiation at UoG The University of Graz (UoG) performs “modern” radiation measurements – as part of the ARAD network (“Austrian radiation”) and “traditional ones” (TAWES = “Teilautomatische Wetterstation”) (credit: M. Mohr)

  6. Atmo II 62 Measuring Radiation at KSO IGAM/IP solar radiation measurements are also performed at KSO (Kanzelhöhe Observatory for Solar and Environmental Research) (UF)

  7. Atmo II 63 Measuring Radiation at KSO KSO is (usually) one of the places with maximum sunshine duration in Austria (above the notorious fog in the Klagenfurt basin (UF)

  8. Atmo II 64 Measuring Solar Radiation Measurement devices for solar radiation employ thermocouples,which use the thermoelectric effect: Thermocouples contain two dissimilar metal conductors in contact, which produce a voltage when heated (Picture credit: M. Mohr).

  9. Atmo II 65 Measuring Solar Radiation Pyranometers are used to measure global and diffuse solar radiation (from the halfspace). The thermopile is composed of several thermocouples, connected in series. The output is a voltage proportional to the temperature difference between the black surface of the sensor element and the housing as reference. Two quartz domes and a ventilation system (shall) minimize external influences (M. Mohr, after Kipp & Zonen)

  10. Atmo II 66 Measuring Radiation Pyrgeometers are used to measure long wave radiation, using a silicon window with a “solar blind” filter, which only transmits the radiation with wavelengths from 4.5 µm up to 42 µm. Pyrheliometers (below) measure direct solar radiation (M. Mohr, after Kipp & Zonen)

  11. Atmo II 67 Measuring Radiation (“traditional”) Most weather stations don’t have sun-trackers, they (may) have two (identical) Star pyranometers, one (left) measuring global solar radiation, the other one (shaded by a shadow ring) measuring (most of the) diffuse solar radiation. The direct solar radiation can only be derived. Star pyranometers measure the temperature difference between black and white sensors (credit: M. Mohr)

  12. Atmo II 68 Global Solar Radiation in Graz, Aug Global Solar Radiation on different summer days (August) (M. Mohr)

  13. Atmo II 69 Global Solar Radiation in Styria, Jan Styrian Climate Atlas, ZAMG:http://www.umwelt.steiermark.at/cms/ziel/16178332/DE/

  14. Atmo II 70 Global Solar Radiation in Styria, July Styrian Climate Atlas, ZAMG

  15. Atmo II 71 Recording Sunshine (“traditional”) In the past, recording of sunshine duration was – literally – done with a “crystal sphere” (Campbell-Stokes autograph) (UF, M. Mohr)

  16. Atmo II 72 Recording Sunshine Duration The “Haenni Solar” device records differences between global and diffuse solar radiation (using rotating strip shades). Sunshine is – by WMO definition (World Meteorological Organization) – when the direct solar radiation, perpendicular to the sun, exceeds 120 W/m2 (M. Mohr)

  17. Atmo II 73 Mean Sunshine Hours in Styria, Jan Styrian Climate Atlas, ZAMG

  18. Atmo II 74 Mean Sunshine Hours in Styria, July Styrian Climate Atlas, ZAMG

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