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USGS CMG InfoBank: Driving the Heat Engine

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Comment: 20:47 - 21:43 (00:56), 1.0 MB
Source: Annenberg/CPB Resources - Earth Revealed - 2. The Restless Planet
Keywords: "David Stevenson", "heat engine", convection Beginner
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Our transcription: The earth is very hot inside and cool on the outside.
This means that there is a large temperature difference.
When you have a temperature difference like this, you can drive a heat engine.
This engine is not too much different conceptually from an internal combustion engine or any other engine that operates with two different temperature reservoirs.
In the case of the Earth, what happens is that that temperature difference is sufficiently large to drive convection, an overturning of the fluid within the Earth, rather similar to what happens when you heat a pot of soup heated from the bottom and produce convection currents within that fluid.
A similar cycling motion seems to occur within the Earth, but at a far slower pace over tens or even hundreds of millions of years.

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Page Last Modified: Thu Oct 31 04:25:16 PDT 2013  (chd)