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Speaker 1: Welcome to brain Stuff production of I Heart Radio. Hey

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Speaker 1: brain Stuff, Lauren Bogabam. Here, I'm looking up into the sky,

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Speaker 1: be it a cloudy day or bright clear night with

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Speaker 1: the stars shining down. It may seem like Earth's atmosphere

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Speaker 1: is a single solid mass, but our sky is more

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Speaker 1: like a lasagna or maybe a trifle, with layers that

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Speaker 1: ripple up and down depending on what's beneath them, and

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Speaker 1: merge into each other in different and interesting ways. And today, though,

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Speaker 1: let's talk about the layer called the stratosphere. But first,

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Speaker 1: we're all creatures of the troposphere. This atmosphere layer is

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Speaker 1: where almost all of the weather related phenomena on planet

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Speaker 1: Earth unfold. Although the troposphere begins at the surface of

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Speaker 1: our planet, its upper boundary is less consistent, and depending

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Speaker 1: on your latitude and the current season, the layer's top

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Speaker 1: might be located anywhere from four to seven miles that's

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Speaker 1: seven to twelve kilometers overhead. Above the troposphere. We have

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Speaker 1: in order the stratosphere, mesisphere, thermosphere, and exosphere. But let's

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Speaker 1: go back and talk about those first two layers more.

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Speaker 1: The troposphere stratosphere boundary or tropopause separates two areas with

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Speaker 1: inverted temperature trends. Inside the troposphere, the global average temperature

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Speaker 1: decreases as you go higher, and yet it's a different

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Speaker 1: story in the stratosphere, where things get warmer as you

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Speaker 1: go higher. Eventually you'll hit the stratosphere's ceiling some thirty

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Speaker 1: miles or fifty kilometers up. Beyond that point, the trend

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Speaker 1: starts to reverse itself. Things get pretty chilly in the mesisphere.

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Speaker 1: You've probably visited the stratosphere once or twice at least.

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Speaker 1: The region's hard to avoid for anyone who travels by

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Speaker 1: air frequented by commercial airlines. The stratosphere is also a

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Speaker 1: bastion of ozone gas and rapid winds, where clouds are

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Speaker 1: scarce but life indoors. The scientists have found microorganisms adrift

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Speaker 1: in the stratosphere. Participants in a study published in August

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Speaker 1: eighteen in the journal Frontiers and Microbiology designed and built

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Speaker 1: an air capturing probe that was installed on a NASA plane.

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Speaker 1: The gadget detected bacteria whizzing around above the local tropopause

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Speaker 1: at altitudes of seven miles or twelve kilometers. UV radiation

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Speaker 1: and extreme temperatures make the stratosphere a rough place for

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Speaker 1: living things to survive up there. Some bacteria depend on

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Speaker 1: sun blocking pigments and protective outer shells. Fast DNA repair

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Speaker 1: is another life saving trick. Hitching rides on storms and

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Speaker 1: volcanic eruptions. Microbes used the stratosphere as an atmospheric super highway. There,

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Speaker 1: winds carry them across the continents at great speeds, allowing

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Speaker 1: the microbes to disperse. The fact that life can tolerate

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Speaker 1: our stratosphere, even for limited periods, could profoundly impact the

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Speaker 1: hunt for, for example, Martian organism. But speaking of life,

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Speaker 1: other stuff in the stratosphere makes most life on Earth possible.

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Speaker 1: Ozone gas safeguards this planet from excessive ultraviolet or UV

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Speaker 1: radiation that's sent to us by the Sun. Made up

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Speaker 1: of oxygen atoms, ozone, like many sunscreens, absorbs UV light.

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Speaker 1: Entire ecosystems would fail if not for that critical service.

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Speaker 1: Our atmosphere supply of the gas is mostly limited to

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Speaker 1: the famous ozone layer, and about this layer is contained

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Speaker 1: within the stratosphere. On a related note, the ozone explains

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Speaker 1: why stratospheric temperatures climb at higher altitudes. Not only does

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Speaker 1: it absorb the Sun's UV rays, but it also soaks

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Speaker 1: up infrared radiation from the troposphere. The result a stratosphere

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Speaker 1: that grows toastier by the mile. Okay, so the troposphere

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Speaker 1: is cloud city, but be they stratos or cumulonimbus. You

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Speaker 1: need water droplets and or ice crystals to make clouds,

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Speaker 1: So the relatively wet troposphere is a great environment for them,

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Speaker 1: but the stratosphere not so much. By and large, it's

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Speaker 1: just too dry to facilitate cloud formation. Still, that cloud

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Speaker 1: shortage isn't a bad thing. The stratosphere combines largely cloud

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Speaker 1: free skies with limited turbulence, making it attractive to airline pilots. Indeed,

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Speaker 1: most commercial planes hit their cruising altitudes in the lower stratosphere.

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Speaker 1: When stratospheric clouds do form, they're sometimes created by the

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Speaker 1: mixing of ice with volcanic dust. Also the polar regions

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Speaker 1: see stratosphere level clouds during the wintertime. That's because the

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Speaker 1: stratosphere is also home to the Arctic seasonal polar vortex,

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Speaker 1: a huge swirling cyclone with a pocket of super cold

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Speaker 1: air on the inside caused by the big temperature contrast

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Speaker 1: of air over the pole versus warmer air from lower latitudes.

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Speaker 1: The vortex collapses every spring and reforms every winter, trapping

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Speaker 1: the coldest air right around the pole. We've been hearing

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Speaker 1: a lot about it the past few years because many

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Speaker 1: scientists think that due to climate change and warmer than

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Speaker 1: usual temperatures, the stratospheric polar vortex is weakening, allowing those

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Speaker 1: ultra cold winds that it normally traps head south. Today's

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Speaker 1: episode is based on the article the Stratosphere where birds

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Speaker 1: and planes fly and bacteria thrives on how stuff works

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Speaker 1: dot Com, written by Mark Mancini. Brain Stuff is production

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Speaker 1: of I Heart Radio in partnership with how stuff Works

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Speaker 1: dot Com and is produced by Tyler Clang. Four more

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Speaker 1: podcasts my heart Radio, visit the heart Radio app, Apple Podcasts,

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Speaker 1: or wherever you listen to your favorite shows