The Slightly-Less-Than-Epic Quest To Measure the Blueness Of The Sky

Illustration for article titled The Slightly-Less-Than-Epic Quest To Measure the Blueness Of The Sky

Some projects meant to gather scientific information end in glory when future generations recognize a visionary endeavor. Others, not so much. Here is the story of the cyanometer, and one man's attempts to measure the blueness of the sky everywhere on Earth.


Inventor, adventurer, man of science, Horace-Benedict de Saussure had a vision. He wanted to gather data about the color of the sky at every time of day, every place in the world, and every altitude. He did this by inventing a "cyanometer," a measurer of blue-ness.

By today's standards, he would have invented paint swatches, but that's somewhat unfair. De Saussure was working in the middle of the 1700s, when exactitude was hard to come by. He used a precise formula to make each shade of paint, and an exact process to apply it to the swatch. There were fifty-two swatches in all. The number zero was white and the number fifty-one was black, and in between was every shade of blue that anyone could wish for. Explorers, mountaineers, and sailors were to carry cyanometers, take them out at various times and various altitudes, and match the numbered swatch to the color of the sky.

Today, very few people are interested in de Saussere's research. Oh, well. Not all avenues of study pan out. However, if you are interested, an average midday sky should be about twenty-three "degrees" on the color scale. The darkest recording was made by the naturalist Alexander von Humboldt, at the top of Mount Teide on Tenerife. It was forty-one degrees.

Anyone suddenly want to go to Mount Teide?

Image: Nikodem Nijaki

[Source: Why the Sky is Blue.]


The funny thing is, measuring the "bluebess" (actually light scattering) is important for aerial photography and remote sensing, so you can correct for it and keep the blue from over saturating the images.