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Warming Demonstrated

1861

Irish physicist John Tyndall demonstrates experimentally that water vapor and other gases warm the atmosphere

John Tyndall, in the article “On the Absorption and Radiation of Heat by Gases and Vapours, and on the Physical Connexion of Radiation, Absorption, and Conduction,” reports on an experimental apparatus to demonstrate and measure the heat-trapping impact of atmospheric gases. His later comment underscores his surprise at this discovery: “Those who, like myself, have been taught to regard transparent gases as almost perfectly diathermanous (transparent to heat), will probably share the astonishment with which I witnessed the foregoing effects… I was indeed slow to believe it possible that a body so constituted, and so transparent to light as olefiant gas, could be so densely opake to any kind of calorific (infrared) rays; and to secure myself against error, I made several hundred experiments with this single substance.”* In 1862, Tyndall provides the following analogy: “As a dam built across a river causes a local deepening of the stream, so our atmosphere, thrown as a barrier across the terrestrial rays, produces a local heightening of the temperature at the Earth’s surface.”** In his 1863 book Heat Considered as a Mode of Motion, Tyndall notes the importance of this finding for conditions amenable to life on Earth: “Aqueous vapour [water vapor] is a blanket, more necessary to the vegetable life of England than clothing is to man. Remove for a single summer night the aqueous vapour from the air which overspreads this country, and you would assuredly destroy every plant capable of being destroyed by a freezing temperature. The warmth of our fields and gardens would pour itself unrequited into space, and the sun would rise upon an island held fast in the iron grip of frost.”***

*Richard Black, “Tyndall’s climate message, 150 years on,” BBC News, September 28, 2011, http://www.bbc.com/news/science-environment-15093234
**John Tyndall, “On Radiation through the Earth’s Atmosphere.” Philosophical Magazine ser. 4, 25 (1863), 200-206; Cited in: Spencer Weart, The Discovery of Global Warming (Feb. 2016), http://history.aip.org/climate/simple.htm#L_M085
***John Tyndall, Heat Considered as a Mode of Motion (1863); Cited in: NASA Data, “Measuring the Earth’s Water Blanket,” https://mynasadata.larc.nasa.gov/science_projects/measuring-the-earths-water-vapor-blanket/

  1861  /  19th Century, Science  /  Last Updated April 24, 2019 by admin-jL  /  Tags: , , , , , , , , , , , , , , ,
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