Wednesday, May 9, 2012

Unexpected expansion.

We had a guest speaker here at work last week, a chap by the name of Pascal Lecomte, from the European Space Agency. He's been working for the past 20 years or so on the some of the various satellites that the ESA have put into space to collect environmental data. There were all sorts of problems you wouldn't immediately think of, not the least of which was data storage - something like 1TB/orbit with a single satellite doing 14 orbits per day. For 365 days a year. For 10-15 years. A metric fuckton of data is the technical term I believe (though not the words he used). Then there's trying to match up surface point records with continuous readings from the satellites, figuring out what to measure, all sorts.

The data that was presented supported the notion that the world is warming, so there was nothing out of the ordinary there. Ocean levels will rise. Only when people talk about ocean levels rising they all tend to talk of the Artic melting, or all the ice in Greenland rolling into the sea. One of the causes that I at least, had failed to see, which Pascal went into, was the thermal expansion of the water. Warmer water occupies a greater volume that the same mass of colder water. And as our oceans warm, they will expand. The current models are looking at about 1mm/year apparently. Not much, but it's another meter's worth of sea rise on top of whatever other water goes into oceans from the melting ice sheets. Not huge, but not insignificant.

For some reason I can't recall right now, when I read this this morning, it put me in mind of Pascal's talk. A University of Washington researcher, Rory Barnes has pulled out his books and done some sums. There's a region around every star called the goldilocks zone, where water exists as a liquid. Only it's probably not quite where we thought it was - for other stars at least, we're fairly sure where our one is. One of the factors that hadn't been taken into account was the gravity of the stars pulling on the internals of the planets that orbit them. This is usually changes because forces due to gravity are related to distance and with elliptical orbits rather than circular ones, a planets distance to it's star is always changing. So gravity pushes and pulls the planets internals, which in turn generates heat from all the friction. Which means that the goldilocks zone probably extends a bit further out than we thought because it's not just the heat from the sun that's contributing to the heat of the planets atmosphere, the planet is as well.

Tidal heating shrinks the 'goldilocks zone' : Nature News & Comment

No comments:

Post a Comment