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- Messwissen von Testo | Im Außenbereich thermografieren
Outdoor thermography
Thermography: knowledge and practice
Special features of outdoor thermography
The IR radiation from clear skies is colloquially referred to as “cold sky radiation”. When the sky is clear, cold sky radiation (~ -50 ... -60 °C) and warm solar radiation (~ 5500 °C) are reflected during the day. In terms of surface area, the sky outweighs the sun, so that the reflected temperature in outdoor thermography is usually below 0 °C, even on a sunny day.
Due to the absorption of solar radiation, objects in the sun heat up. This influences the surface temperature significantly - sometimes even hours after exposure to sunlight.
Tips and tricks for outdoor thermography
It is best to take measurements in the early morning hours and/or when the sky is densely cloudy. But it shouldn't rain or snow. Fog or strong wind are also unfavorable.
Change your position while measuring to detect reflections. Reflections move, thermal abnormalities in the measurement object remain in the same place - even when the viewing angle changes.
Avoid measurements near very hot or cold objects or shield them.
Avoid direct sunlight, even a few hours before the measurement. Also note the cloud cover a few hours before the measurement.Do not measure on the thermal imaging camera if there is condensation of humidity.
Do not measure in heavily contaminated air (e.g. freshly blown dust).
Theoretical basics of thermography
Find out more about the physical basics of thermography in our compact tutorial. A real advantage for e.g. B. to set the correct emissivity for each surface.
