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NASA Why? Files segment describing how atmospheric particles are transported over distance by wind.
Hi, I'm Dr. Jennifer Olson. I'm one of the treehouse detectives. We're trying to learn more about wind
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We want to know if volcanic ash can blow all the way from the Pacific Ocean to Virginia
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I'm looking at some data in the cave right now. Would you like to step in with me and take a look?
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I've heard of the cave. Sure. Let's go. First. You'll need to take off your shoes and put on the glasses
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Wow, this is neat. We're looking at wind vectors over the Pacific Ocean in the US
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What's a wind vector?
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Do you see the yellow arrows?
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Yeah, lots of them.
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Those are wind vectors. They show which direction the wind is blowing. Their size tells you how fast the wind is blowing.
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The longer the arrow is, the faster the wind speed is.
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What about the wind vectors way up there?
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These vectors are up at 12 miles over the Earth's surface. That's well above the weather.
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It looks like all those arrows are pointing in the same direction. Is that normal for high altitudes?
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Yes, it is. Notice that these arrows are mostly pointing from the west toward the east. That's a zonal direction in the global wind pattern.
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How fast are they blowing?
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At 12 miles up, most wind speeds are between 40 and 50 miles per hour. At these altitudes, there's also something that we call a jet stream.
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Oh, you mean the white stuff that comes out the back of a jet we see?
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Yes, but the jet stream is a river of very fast-flowing air, where speeds can reach several hundred miles per hour.
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That's as fast as a major tornado.
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Let's step outside and go to my computer lab.
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Okay.
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So what's the second thing that affects how far wind can transport particles?
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It's the lifetime of a particle.
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Scientists have a tremendous amount of data available to them to study things like lifetimes of gases and particles,
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and much of that data is stored here at the Atmospheric Science Data Center.
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I didn't know particles had a life.
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Yes, lifetime refers to how long the particle stays in the atmosphere.
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For a particle near the surface, ash and dust will be rained out of the atmosphere within a matter of days.
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So volcanic ash would not have a very long lifetime.
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Not necessarily.
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If the ash were injected up in the atmosphere, near the stratosphere, its lifetime could be very long, in the order of weeks or months.
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Would zonal winds then be able to carry the ash to Virginia?
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Yes, it could.
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If a volcano injected particles into the stratosphere,
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it could be transported for very long distances by the very fast wind speeds of the jet stream.
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Yeah, but the Pacific Ocean is so far away.
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That would take forever.
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Let's do a quick calculation.
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It's about 7,000 miles from here to Mount Luminous.
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If we take a typical atmospheric wind speed of about 40 miles per hour,
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what do you get?
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175 hours.
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175 hours to transport the dust to Virginia.
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That's about a week.
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In fact, the dust plume could be transported completely around the globe in about a month.
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The sky is so deep red.
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Is there anything about this eruption that is different?
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Yes, there is.
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I read that this volcano also injected a lot of sulfur dioxide and water vapor into the stratosphere.
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These two gases react together to form tiny sulfuric acid particles.
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We learned from Dr. Poluski that particles scatter the blue light.
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That's right.
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And these particles are small enough that they act with the molecules in the atmosphere
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to scatter even more of the blue light from the sun's rays.
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Thanks, Dr. Olson.
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Sure.
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- Idioma/s:
- Niveles educativos:
- ▼ Mostrar / ocultar niveles
- Nivel Intermedio
- Autor/es:
- NASA LaRC Office of Education
- Subido por:
- EducaMadrid
- Licencia:
- Reconocimiento - No comercial - Sin obra derivada
- Visualizaciones:
- 214
- Fecha:
- 28 de mayo de 2007 - 15:32
- Visibilidad:
- Público
- Enlace Relacionado:
- NASAs center for distance learning
- Duración:
- 03′ 19″
- Relación de aspecto:
- 4:3 Hasta 2009 fue el estándar utilizado en la televisión PAL; muchas pantallas de ordenador y televisores usan este estándar, erróneamente llamado cuadrado, cuando en la realidad es rectangular o wide.
- Resolución:
- 480x360 píxeles
- Tamaño:
- 20.02 MBytes
