More Travel Tips:
Exploring the Arctic from Space 17 Jan 2012
gt;gt; This is a view of the earththat you probably not familiar at looking at all the time, looking down overthe North Pole. Here you've got theArctic Ocean, it's about 14 million squarekilometers, and it's surrounded by land on all of its sides,but then you have these regions where water can flowin and out in here through the Bering Strait, intothe North Pacific, and then here
through Fram Straitand the Davis Strait into the North Atlantic. In the winter, the temperaturesacross the ocean on average get down to about minus 30. And because of thesecold temperatures, the sea waters freezeand it forms a layer of ice known as sea ice. And over average,the ice is about 2,
2 and half meters thick, and below it is kilometersof the ocean. And in the winter, that icecompletely fills the Arctic basin and even reaches out through the BeringStrait into the Bering Sea. Now in the summer, thatice cover starts to retreat as the temperatures getwarmer and in the summer. The average temperatureacross the Arctic Ocean is
around 0 degrees, and this tutorial that you've been watching hereshows the summer September ice extent minimum. It's from the National Snowand Ice Data Center in the USA, and some of you mightbe familiar within the press everyyear around September, you see headlines about we'vereached another minimum arctic sea ice extent, andit's a downward trend
since the satelliterecords began in 1979. So, and then you oftenget kind of speculation about when the arctic icecuff is going to be icefree in this summer, and whether theNorthwest Passage will be open. And we can go backto PowerPoint now. The background noise, thisis in the melting and freezing of the ice inaudible, thatthe ice kind of changes. The ice is also moved aroundby the wind, it's dynamic.
And what you're lookingat here is a tutorial that I took while I wason an ice company arctic. And its two icebergs, basicallybeing blown by the wind and they crush in together,there's actually the sound that you could hear, justbefore they lowered the volume, was the sound of actually theice inaudible, the ice pushing up against each other. So as the ice isbeing moved around,
Hi, I'm Liz Cottrell, director of the GlobalVolcanism Program at the National Museumof Natural History. I'm standing here in the Geology, Gems,and Minerals Hall in front of the Earthquakes andEruptions exhibit. We know that watching asingle volcano erupt is
totally awesome, but what can watchingall volcanoes erupt throughout the course ofearth history tell us about how the planet worksé Let's take alook and find out. We're looking here at amap of the world we see the familiarcontinents and oceans, but we don't see thetectonic plates or the
plate boundaries. Rather thanmemorizing where they are, let's collect some data. I have started a tutorialplaying that's recording earthquakes anderuptions since 1960. Every time an earthquakehappens a dot appears and every time a volcanoerupts a triangle appears. One of the first things youwill notice is that earthquakes
and eruptions aretaking place all of the time. Way out in the middle of theocean we see all kinds of tiny white dots appearing. Earthquakes are happening 247out in the middle of the ocean, deep below the waterwhere you can't see it. What's causingthese earthquakesé Actually it isvolcanic eruptions.
Volcanoes are erupting allthe time on the sea floor and they causeearthquakes to take place. So even though we can'tsee the volcanic eruptions, that's what isdriving the earthquakes. What about the middleof the United Statesé Or the East Coasté Nothing is happening. It doesn't look likethat is a plate boundary.
In fact if we look aroundthe entire edge of the Atlantic Ocean we seehardly any activity. There are noplate boundaries. The only plate boundary inthe Atlantic runs down the middle of the ocean,a divergent margin, the MidAtlantic Ridge. Bang! We just heard a bigsymbol crash in 1980 when