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Horace-Bénédict de Saussures cyanometer, 1760

A cyanometer (Greek) is an instrument for measuring the intensity of the blue color of the sky . This measuring device was developed by Horace-Bénédict de Saussure towards the end of the 18th century.

From the measurement, conclusions can be drawn about the nature of the atmosphere : the less water it contains in the vaporous state , the more transparent it or the sky the bluer .

Alexander von Humboldt carried  a cyanometer with him on his research trip to America (1799–1804), which he is said to have acquired in Paris in 1798 .

Note on the blue of the sky: In 2006, researchers at the British National Physical Laboratory used a colorimeter to identify Rio de Janeiro , New Zealand and Australia as the places with the strongest blue in the sky.


Individual evidence

  1. Sky blue in 53 levels. In: August 13, 2014, accessed on September 14, 2019 (illustration of a cyanometer).
  2. Broadcast on April 14, 2010. (No longer available online.) In: BR alpha, Planet Wissen. Formerly in the original ; accessed on September 14, 2019 .  ( Page no longer available , search in web archives )@1@ 2Template: Toter Link /
  3. Rio has the brightest blue: Researchers determine the place with the most intense color in the sky. In: August 30, 2006, accessed September 14, 2019 .