Measure the Sky's Blueness with a DIY Cyanometer
A Cyanometer and a Cloud Colourimeter
Inspired by spring skies, Byopia Press shares a DIY cyanometer, a device invented in 1789 by Horace-Bénédict de Saussure to measure the blueness of the sky. The post includes printable templates for the cyanometer and a new cloud colourimeter, plus examples from artists like Olafur Eliasson and Martin Bricelj Baraga, and even a knitted version.
The sky is not the same blue everywhere since things like air pollution affect the colour.