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Air Pressure
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NASA Why? Files segment explaining how air pressure affects weather.
Wow we learned a lot from Dr. Chambers. I wrote this for my trip. Don't forget to
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add water vapor and condensation. I know that's a clue because it's how rain is
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made. Hi where's Dr. D? Is he here today? We haven't seen him yet. Hi guys I'm here.
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You have that look like you're working on something. We're concerned about
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missing our physics fair because of the storm. We don't want to miss riding those
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roller coasters. Can you give us some clues on how to understand the weather?
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Sure. Something you definitely need to understand is energy. There's an electric
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motor that provides the energy to raise a roller coaster car to the top of the
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first hill and then gravity takes over. What energy source makes the weather
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happen? Do you mean what makes the winds blow? Or what raises the rain into the
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clouds just like the roller coaster was lifted? Exactly. I don't know. I think you
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do. It's the same energy source that makes the plants grow. Oh the Sun I knew
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that. When the Sun heats the earth, some areas become hotter than others. This is
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uneven heating that produces the winds. Wind? It can make wind? Air always moves
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from a region of higher pressure to a region of lower pressure. Wait Dr. D we
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haven't learned about pressure yet. What's that? I guess I better slow down a little
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bit. Air is made up of molecules like oxygen and nitrogen. They're constantly in motion
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traveling in straight lines until they bounce off of something. So you mean right
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now we're being bombarded with molecules? That's right.
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Molecules bounce off of something and they apply a force to that object. This force
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creates what we call air pressure. Let me show you an example. These hemispheres have
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molecules bouncing off the outside. I've taken most of the air out of the middle
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so there are very few molecules on the inside pushing out. Here try to pull it
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apart. Wow this is really hard. That force you talked about is very real. Now if I
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let the air back into the middle we'll have molecules both pushing out and
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pushing in. The pressure on the outside is the same as the pressure on the inside. It
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shouldn't be a problem. It's much easier now. Let's try something else. Put on your
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goggles and safety glasses.
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I'm gonna heat the air inside this can. There's a little bit of water in it.
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I'm gonna turn the can upside down into the pan of water and the pressure in the
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can is gonna drop very very quickly and the higher pressure air on the outside is
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gonna crush the can.
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Watch this. That's amazing. Now when I blow up this balloon I'll be increasing the
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density of the air inside. That means the molecules will be more tightly packed.
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This makes the pressure on the inside greater than the pressure on the outside.
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I knew that was going to happen. So that's what you meant when you said the
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air went from a region of higher pressure like the balloon to a region of
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lower pressure like this room. Very good. Now suppose you're at the beach in the
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summer. The sand is hot and it warms the air above it. Now warmer air has a lower
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pressure than cooler air because it's less dense. Now the air above the ocean
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is cooler therefore it has a higher pressure than air above the sand. What
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happens? Well I would think just like the balloon that the wind will blow from the
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higher pressure air across the ocean toward the lower pressure air on the
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beach. Very good. That's what's called a sea breeze.
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There's an update from the Weather Channel. The problem that we reported earlier has slightly strengthened and
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become more organized with maximum sustained wind now at 30 miles per hour.
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This system has been upgraded to a tropical depression. It is currently
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located at 15 degrees north and 40 degrees west and it is moving northwest
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at 20 miles per hour. Here's a globe. Look here are the Antilles Islands. I think we
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should start tracking the storm. Don't you? Oh I don't think so. It's far away. We
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don't need to worry about it. Yes we do. The storm has turned into a tropical
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depression. I don't want to miss the physics fair or our trip to Florida.
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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:
- 284
- Fecha:
- 28 de mayo de 2007 - 15:33
- Visibilidad:
- Público
- Enlace Relacionado:
- NASAs center for distance learning
- Duración:
- 04′ 08″
- 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:
- 24.85 MBytes
