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Coastal Currents

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Subido el 28 de mayo de 2007 por EducaMadrid

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Twelfth segment of the Ocean Odyssey describes coastal currents and how they might effect oil spills and objects in the ocean.

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Hi, R.J. I'm glad you found me. Dr. D. said you'd be coming by. 00:00:00
Hi, Dr. Moisen. We're trying to figure out the final pieces to our mystery. 00:00:04
Well, we had some tennis shoes washed up on the beach, and we don't know where they came from. 00:00:08
That sounds like a real mystery. 00:00:11
It really is. We think that the shoes came from someplace far away, 00:00:13
and that the ocean currents brought them to Virginia. 00:00:17
That's very possible. 00:00:19
We know that the Gulf Stream flows along the coast of Virginia. 00:00:20
We're not sure how the shoes got from the Gulf Stream onto the shore. 00:00:23
Dr. D. suggests that we come learn more about coastal currents. 00:00:26
Are coastal currents different? 00:00:29
Yes, they are. 00:00:30
Coastal currents can be located on the surface or on the bottom of the ocean, 00:00:31
and they can be formed by density differences or tidal processes, 00:00:35
but they're always found near the shoreline. 00:00:38
Well, it doesn't sound like they're the answer. 00:00:40
They could be, but first let's talk about dispersion. 00:00:42
What's dispersion? 00:00:45
Suppose you placed 100 yellow ducks in the center of a pool, 00:00:46
turned off the pumps, and went away for 24 hours. 00:00:49
Where do you suppose the ducks would be when you came back? 00:00:51
Probably in the center of the pool, because there aren't any currents to move them around. 00:00:54
Actually, you would find them randomly distributed or dispersed throughout the pool. 00:00:57
Why wouldn't the ducks all be in the same place? 00:01:01
Small-scale circulation patterns in the pool that move the water around 00:01:03
will actually affect where these objects in the pool go. 00:01:07
It could be something as small as a gust of air. 00:01:10
But if the tennis shoes came from far away, they floated in currents that were already moving. 00:01:12
Yes, but major currents have lots of eddies, filaments, swirls, 00:01:17
and even jets that interact with and move objects. 00:01:20
Where do eddies and filaments? 00:01:23
Eddies are formed when a current doubles back to form a small whirl, 00:01:24
and filaments are meanders that come off from the current. 00:01:28
So maybe the eddies or filaments brought the tennis shoes into the shore. 00:01:31
That's possible, because shoes caught in these small currents 00:01:34
could travel across these major currents. 00:01:37
Does the Gulf Stream have any eddies or filaments? 00:01:39
Yes, lots of them. 00:01:41
There are even large circulation eddies that break off from the Gulf Stream. 00:01:42
I think that's the answer to our oil glob mystery, 00:01:46
the loop current in the Gulf of Mexico. 00:01:48
Now for the shoe mystery. 00:01:50
Do coastal currents complete the process of bringing the shoes on shore? 00:01:53
Yes, they can, but most of the shoes would not make it. 00:01:56
If they float, won't they eventually end up on shore? 00:01:58
No, most will end up in the Sargasso Sea. 00:02:01
That's the place in the Atlantic Ocean with a lot of seaweed. 00:02:03
Why there? 00:02:06
Large circulation gyres in the North Atlantic Ocean move in circular clockwise pattern. 00:02:07
Floating objects within these waters tend to move towards the center of rotation. 00:02:13
I guess if the coastal currents could bring the shoes on shore, 00:02:17
now all you have to do is find out where the container fell off the ship. 00:02:20
Sounds like a good idea. 00:02:23
And if the location's right, 00:02:24
we will then know if it's possible that the currents, dispersions, 00:02:26
and coastal currents brought them on shore. 00:02:29
Thanks, Dr. Moisen. 00:02:31
You're welcome. Glad I could help. Keep me posted. 00:02:32
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Idioma/s:
en
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:
537
Fecha:
28 de mayo de 2007 - 15:34
Visibilidad:
Público
Enlace Relacionado:
NASAs center for distance learning
Duración:
02′ 35″
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:
15.69 MBytes

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