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Into the Future with Metrology - The Challenges of Our Environment and Climate


How humid, how warm?

DLR's HALO research aircraft above the rainforest. Also on board: HAI, PTB’s highly accurate humidity measuring instrument specifically developed for use in airplanes and in clouds.

Everyone talks about carbon dioxide – but plain water in the form of humid air is one of the strongest greenhouse gases. In other words, it is an essential climate variable. PTB is one of the main participants in the broad introduction of the metrological principle of traceability for the measurands of water content and gas humidity, thus making the measurements more reliable and comparable. With the HAI and SEALDH laser hygrometers, it has developed the world's first airworthy, calibration-free H2O-transfer standards – in addition to its existing primary standard – and has successfully used them on renowned research aircraft such as Opens external link in new windowHALO and LEARJET. Opens external link in new windowHAI is an extremely fast hygrometer developed especially for use on airplanes even when traveling through clouds. It is the only instrument in the world that can simultaneously and precisely determine which part of the water is present in the atmosphere as droplets or ice particles and which part is present in the gas phase. This data helps to better understand natural and man-made cloud formation processes and their influence on the climate. PTB is working (beyond the radiation-thermometric and radiometric methods of remote sensing) on measurement concepts that can be used to determine the temperatures of atmospheric layers better than before by means of high-resolution molecular spectra.


Participating departments
Opens internal link in current window3.4 Analytical Chemistry of the Gas Phase

Opens internal link in current window 7.3 Detector Radiometry and Radiation Thermometry