Tyndall, John (1820–93)

JOHN TYNDALL WAS born in Leighlinbridge, County Carlow, in Ireland on August 2, 1820. After working as a surveyor and a mathematics teacher, he attended the University of Marburg in Germany, where he received his Ph.D. In 1854, he became a professor of natural philosophy at the Royal Institution in London (a scientific research center founded in 1799). In 1867, he was made superintendent of the institution, taking over from Michael Faraday.

Tyndall's most well-known scientific studies included the nature of sound, light, and radiant heat and observations on the structure and movement of glaciers. Glaciers had become a scientific area of interest during that time because in the 1830s, Louis Agassiz (considered the father of glaciology) had discovered that a large portion of Europe and North America had once been covered with ice.

Tyndall developed an interest in meteorology as a result of his love for mountain climbing. He studied alpine glaciers and took meteorological [Page 990]measurements on Mont Blanc in the Alps. Using a spectrophotometer he designed, Tyndall studied the absorption of infrared light (at the time called radiant heat) by atmospheric gases. Infrared light is felt as heat and has wavelengths of approximately 0.7 to 1.0 μm. Visible light for comparison has wavelengths of approximately 0.4 to 0.7 μm.

John Tyndall was a 19th-century physicist. He is renowned for his studies in the absorption of heat by atmospheric gases.

Some of the invisible gases (oxygen, nitrogen, and hydrogen) were transparent to radiant heat, whereas water vapor and carbonic acid (now known as carbon dioxide) absorbed and reemitted infrared light, thereby warming the atmosphere close to the earth. From these experiments, Tyndall realized that water vapor, carbon dioxide, and ozone—even in small quantities—were the best absorbers of heat radiation, and he later speculated on how changes in these gases could correlate to climate change.