Download presentation
Presentation is loading. Please wait.
Published byLiliana May Modified over 9 years ago
1
(3) Measuring Radiation Physics of the Atmosphere II Atmo II 57
2
Measuring Radiation Christoph Bichler Atmo II 58
3
Measuring Radiation Atmo II 59
4
Measuring Radiation 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 shaded pyranometer. G = S cosθ + H UF S G H Atmo II 60
5
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) Atmo II 61
6
Measuring Radiation at KSO IGAM/IP solar radiation measurements are also performed at KSO (Kanzelhöhe Observatory for Solar and Environmental Research) (UF) Atmo II 62
7
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) Atmo II 63
8
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). Atmo II 64
9
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) Atmo II 65
10
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) Atmo II 66
11
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) Atmo II 67
12
Global Solar Radiation in Graz, Aug Atmo II 68 Global Solar Radiation on different summer days (August) (M. Mohr)
13
Global Solar Radiation - Eclipse Atmo II 69 Global Solar Radiation on sunny days with and without partial solar eclipse, and on a cloudy day in comparison (IGAM).
14
Global Solar Radiation in Styria, Jan Atmo II 70 Styrian Climate Atlas, ZAMG: http://www.umwelt.steiermark.a t/cms/ziel/16178332/DE/
15
Global Solar Radiation in Styria, July Atmo II 71 Styrian Climate Atlas, ZAMG
16
Recording Sunshine (“traditional”) In the past, recording of sunshine duration was – literally – done with a “crystal sphere” (Campbell-Stokes autograph) (UF, M. Mohr) Atmo II 72
17
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/m 2 (M. Mohr) Atmo II 73
18
Mean Sunshine Hours in Styria, Jan Atmo II 74 Styrian Climate Atlas, ZAMG
19
Sunshine in January? Atmo II 75 Sometimes, sunshine is a rare event during winter months.. (IGAM)
20
Sunshine in January! Atmo II 76 Above the low-level clouds this can be entirely different.. (UF)
21
Sunshine in November Atmo II 77 Under the low-level clouds you might not believe it.. (UF, IGAM)
22
Mean Sunshine Hours in Styria, July Atmo II 78 Styrian Climate Atlas, ZAMG
23
Increased Sunshine Atmo II 79 A part of the strong warming in Austria during the past ~35 years is due to increased sunshine (less clouds) in the same period (HISTALP)
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.