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SYFY WIRE Bad Astronomy

Science is in the air

By Phil Plait
A satellite/computer map showing the movement of aerosols, particles suspended in the air, over part of the northern hemisphere. Credit: NASA's Goddard Space Flight Center

Every now and again, I ask you to indulge me for a moment or two, because there's a point I want to make that may not seem obvious from the actual science I present in an article. In this case, let's start with the beauty of our planet.

The NASA video below depicts much of the western part of the northern hemisphere of Earth. Using satellite observations combined with computer simulations, the video tracks aerosols — particles suspended in the air — from July 31 to November 1, 2017. The aerosols tracked are sea salt (blue), dust (tan/brown), and smoke (white). The interaction of water, air, and aerosols is, quite simply, utterly mesmerizing.

One of the most striking aspects I noticed was how oceans winds whip up the sea salt from the water surface, making hurricanes so visible (without that you wouldn't see the hurricanes at all in this visualization). That never occurred to me, but it seems so obvious in hindsight: I've stood on beaches on windy days and tasted salt on the air. So of course that salt gets moved around by wind, but the sheer amount of it depicted in the video is a bit staggering.

Another part I found interesting was how the dust from the Sahara travels. I tend to think of winds generally moving west to east at my own location, but that changes with latitude. Not too far south the wind tends to move westward, so that fine dust from north Africa makes its way toward the US. … except when Hurricane Ophelia took the very unusual track to the northeast, picking up that dust (and smoke from fires in Portugal) and sweeping it to the North Atlantic and further to the North and Baltic Seas. That’s a change of 40° or so in latitude! That's a vast swath to be affected by something that started off locally in the western Sahara.

Also, keep your eyes on the U.S. northwest up into Canada. Raging wildfires there produced huge amounts of smoke — you can see individual fires in the video — and transport that all the way across Canada and over the Great Lakes.

Watching this, I was struck over and over again at how our planet is interconnected. Nothing happens anywhere without it affecting everywhere. Even if it's not a direct impact — say, that smoke from the western fires only reaching to the Great Lakes — how does that affect the weather and conditions at that final spot? Say the smoke cooled the Lakes by a half-degree or so. What happens to the weather patterns farther east due to that?

This is precisely why scientists use computer simulations like this. The Earth is what we call a nonlinear system: Just because you change some condition by a little bit doesn't mean something else changes by a little bit. Every little change has effects all down the line. And those can then change the initial change, making it smaller or bigger, and round and round we go.

But take a step back. The video you just saw wasn’t produced by some Hollywood VFX company, made up out of thin air. This isn't Photoshop, there's no pre-made button to click to make wind look real or cyclones to spin. This isn't an animated CGI artist's vision, it's a simulation based on reality, based on actual observations from satellites above the Earth coupled with actual physics formulae to determine the parameters of the simulation.

This is all based on mathematical equations that are solved based on the physics they represent.

It's used to break down or add in different factors to see how they each contribute to the overall planetary environment, and just as important to see how they interact with each other. This is then used to narrow down the parameters that get fed into those equations, use our better models to create a better understanding of how the Earth behaves.

And here's the kicker: It works. We really do have an excellent grasp of the fundamental physics and mathematics of climate and weather and atmosphere and water. We've had that for quite some time. The complexity comes from the interactions, from the ways things can change drastically with small changes, with how the wind might blow this way instead of that. Computer simulations based on data help the models be better.

This stuff works. And these are the same physics, the same the math, the same scientists in many cases, that are also telling us that the planet is warming up. The interaction of sunlight, carbon dioxide (and other greenhouse gases), and the surface of the Earth is very well understood. Again, the complexity comes from the interaction of the many moving parts, but the overall effects are very well understood indeed.

There are those who will tell you the models don't work. Those people are wrong. There are people who will tell you the science isn't understood. Those people are wrong. There are people who say human activity isn’t causing this. Those people are wrong. There are people who will tell you we don’t understand enough about this to take any action. Those people aren't just wrong, they're dead wrong. We can take action. We must take action.

Happily, many are taking action. Our own government right now is moribund about new and renewable energy technology, doing every thing it can to prop up coal and fossil fuels while delaying green tech. But even as they do so wind and solar make leaps and bounds in production, efficiency, and cost.

The science on this is clear, as clear as the wind in the video. And those winds are blowing toward change.

Via Mike Okuda and Jeff Berardelli