Moment of Science: The Origins of Weather

A multibillion-year journey from the dust of the universe to your own backyard
Published: Sep. 14, 2021 at 4:19 PM EDT|Updated: Sep. 14, 2021 at 5:31 PM EDT
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TOLEDO, Ohio (WTVG) - Love it or hate it, weather is a constant in our lives... but how did it all get started? Let’s take a look back -- 5 billion years or so -- and find out.

Planet Earth started to form out of a spinning disk of gas and mass, perfectly distanced from the Sun to sustain life (though not yet... not by a longshot). As any real estate agent will tell you, location is key. At this point, it was still way too hot to retain liquid water, so we wouldn’t have an atmosphere yet... and even when we got one, it contained up to 200x as much carbon dioxide as today’s atmosphere. We finally got somewhere when the planet’s surface cooled and formed a crust about half a billion years later.

As for how we actually got all the water we have today, one theory involves icy asteroids striking Earth during what’s called the “Late Heavy Bombardment”, though volcanoes and the like would later release water vapor through “outgassing”. At first, oxygen was only in that newly-melted water, none of it in gas form yet (in fact, most of the atmosphere was methane up to 2.5 billion years ago).

Enter “cyanobacteria”, imaginatively named because they look greenish-blue. They took that CO2, mixed it with sunlight and water, and created that oxygen gas through photosynthesis. It took another 500 million years or so to clear the air, as it were, and oxygen finally overtook methane -- voila, blue skies!

Those oxygen levels were still way below today’s level of 21%, but a sudden surge may well have been responsible for “The Cambrian Explosion”, where ancient seas were teeming with life almost overnight -- if by overnight, we mean several million more years.

That surge about 400 million years back drew a lot of the CO2 out of the air, helping to cool the Earth even further and balance the atmosphere. Gradually, the water cycle of evaporation, condensation, clouds and rain that we know and love and/or hate today became a permanent fixture.

That’s the short answer for how air, water and weather began... but it’s been more of an uphill battle for one of Earth’s newest species to understand it all. Our earliest evidence of trying to forecast comes from Babylon in 650 BC. 3 centuries later, Aristotle wrote a paper called “Meteorologica” -- sound familiar? The word actually does come from “meteors”, which really describes anything falling from the sky including rain, snow, and ice. Aristotle had some errors, of course, but a lot of his theories were pretty sound -- how tornadoes form, lightning creating thunder, even a spherical Earth was factored in!

As technology got better through the centuries, we got better at predicting what might happen to the weather... though there’s a reason a meteorologist coined the term “chaos theory”. We’ve come very far, but we’ve got a long way to go.

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