August 2 – What a gas!

Today’s factismal: John Tyndall was born 193 years ago today.

Ever since there have been three year-olds, there’s been the question “Why is the sky blue?” And ever since John Tyndall, we’ve known the answer to that question. Born in Ireland to a family of moderate means, he was originally trained to be a surveyor. The mathematics of the job fascinated him, and he soon forsook the physical labor of surveying for the hallowed halls of the University of Marburg, where he studied under such luminaries as Robert Bunsen (of burner fame) and Gustav Magnus (of curveball fame). He soon graduated and went to work researching magnetism.

John Tyndall (Image courtesy Tyndall Institute)

John Tyndall
(Image courtesy Tyndall Institute)

At the time, light was just starting to be recognized as an electromagnetic phenomenon and it was a natural transition for him to start investigating the effects of “radiant energy” (the energy carried by light). Among his first experiments was a series of tests on nitrogen, oxygen, and carbon dioxide, looking to see how they would react to radiant energy. He thus performed the first experiment demonstrating what would come to be known as the greenhouse effect; as the concentration of carbon dioxide in the air increases, the temperature rises. His work was well-received and duplicated across the globe almost immediately after its publication in 1859, and led directly to the first prediction of how the Earth’s temperature would change as the CO2 increased.

Shortly after that, Tyndall became fascinated by the way that particles suspended in the air would scatter the light and change the color. He discovered that smoke (like that from a pipe or a coal stove) would appear slightly blue, and that the more particles there were in the smoke (i.e., the less complete the burning was), the bluer it seemed. He realized that the light was being bounced in all directions by the particles and that blue light was able to pass through more easily because it had the longer wavelength; in effect, it bounced off of fewer particles and so was less likely to be absorbed.

The mountain haze appears blue thanks to the Tyndall effect (My camera)

The mountain haze appears blue thanks to the Tyndall effect
(My camera)

Though many thought (and some still do) that he had answered the question of “Why is the sky blue?”, it turned out that he hadn’t. But what he had done was point the way toward the real answer, which was found just a few years later. (His answer was wrong because the particles in smoke are too big to scatter enough light to make the sky blue.) But he was happy to have helped move us closer to the answer.

And that’s what citizen scientists do. By collecting data, they help other researchers get a little closer to the day when we’ll be able to answer all of those other questions that a three year-old asks. Questions like “Why are there clouds?” (It turns out that is a harder question to answer than you might think.) If you’d like ot help, then why not go back to S’COOL (Students’ Cloud Observations On-Line) Roving Observer?

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