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Re: no leap second coming in December
From: Frank Reed CT
Date: 2004 Jul 29, 14:05 EDT
From: Frank Reed CT
Date: 2004 Jul 29, 14:05 EDT
Geoffrey K wrote:
"Probably the New Scientist magazine. But
the gist of it was that sufficiently large bodies of water have now been
trapped in latitudes lower than they would otherwise occupy, that the
effect on the Earth's angular momentum is measurable and has had to be
accounted for by the odd leap second or so."
That would explain it. It seems that the editors of 'New Scientist' never miss an opportunity to exaggerate <g>. There was a small article pubished in a scholarly journal maybe five years ago in which the author demonstrated that there is a lot of mass in all of those manmade lakes (and there is! it's a huge amount of mass by an standards). Since the distribution is different from the natural uniform distribution of water over the Earth's oceans, there should be a corresponding difference in angular momentum. And of course there is --it's a trivial calculation. But it's very small. In principle, it would be measurable as a change in delta-t over the course of a few centuries IF all other things could be held constant, but of course they can't so this is more of a "thought experiment" than an issue of observable dynamics. Unfortunately, some of the reporting on this story made it sound as if there was an observable change in the hard data. That is not the case.
Frank R
[X] Mystic, Connecticut
[ ] Chicago, Illinois
"Probably the New Scientist magazine. But
the gist of it was that sufficiently large bodies of water have now been
trapped in latitudes lower than they would otherwise occupy, that the
effect on the Earth's angular momentum is measurable and has had to be
accounted for by the odd leap second or so."
That would explain it. It seems that the editors of 'New Scientist' never miss an opportunity to exaggerate <g>. There was a small article pubished in a scholarly journal maybe five years ago in which the author demonstrated that there is a lot of mass in all of those manmade lakes (and there is! it's a huge amount of mass by an standards). Since the distribution is different from the natural uniform distribution of water over the Earth's oceans, there should be a corresponding difference in angular momentum. And of course there is --it's a trivial calculation. But it's very small. In principle, it would be measurable as a change in delta-t over the course of a few centuries IF all other things could be held constant, but of course they can't so this is more of a "thought experiment" than an issue of observable dynamics. Unfortunately, some of the reporting on this story made it sound as if there was an observable change in the hard data. That is not the case.
Frank R
[X] Mystic, Connecticut
[ ] Chicago, Illinois
