What Exactly is the Greenhouse Effect?
If it weren’t for the greenhouse effect, life on Earth as we know it would not exist. But what is it exactly? And who discovered it? Back in the early 1820s when James Monroe was the American president, Jean-Baptiste Joseph Fourier, a French mathematician and physicist determined that the Sun was too far from the Earth to warm it enough to sustain life. He eventually concluded that gases in our planet’s atmosphere must be trapping the Sun’s heat.
Spencer Weart, the author of The Discovery of Global Warming, describes how Fourier understood the process. He wrote, “Energy in the form of visible light from the Sun easily penetrates the atmosphere to reach the surface and heat it up, but heat cannot so easily escape back into space. For the air absorbs invisible heat rays (“infrared radiation”) rising from the surface. The warmed air radiates some of the energy back down to the surface, helping it stay warm.”
Three decades later, just before the American Civil War began, the experiments of an Irish physicist named John Tyndall proved Fourier right. Tyndall discovered that oxygen, nitrogen, argon and hydrogen are mostly transparent to the Sun’s reflected heat but “molecules of water vapor, carbon dioxide, and ozone” serve as a kind of blanket, trapping the Sun’s heat and keeping the Earth warm.
Tyndall wrote, “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... and the sun would rise upon an island held fast in the iron grip of frost."
In fact, Earth would be a frozen, lifeless rock without these special gases. What makes them special? It’s their molecular structure. Our atmosphere is mostly nitrogen and oxygen molecules, which according to the University Corporation for Atmospheric Research, contain only two atoms which “are bound together tightly and unable to vibrate, so they cannot absorb heat and contribute to the greenhouse effect.”
Molecules of greenhouse gases, like carbon dioxide, contain at least three atoms, which are “held together loosely enough that they vibrate when they absorb heat. Eventually, the vibrating molecules release this heat, which will likely be absorbed by another greenhouse gas molecule. This process keeps heat near the Earth’s surface.”
November 19, 2019
