Viridian Note 00296: Planetary Rotation

Key Concepts: Greenhouse effect, slowing of planetary rotation, lengthening of Earth's day

(((An eager reader asks: "Have the events of the last few months sent the Viridian forces into a fetal curl from the horror, the horror of it all?" No. During the hiatus since Viridian Note 00295, I've visited both the Pentagon and the World Trade Center. If that doesn't do it for you fetal-wise, nothing will, and that didn't do it for me. I wrote a long article on the military for WIRED, and I also attended the Davos World Economic Forum, cops, zillionaires, protesters, and all. I've been a busy guy. Viridian readers who wonder if the Pope is in catatonic shock should check out this site:)))

(((If SCHISM MATRIX is still shipping its daily commentary, then very likely I'm still alive and kicking.)))

The Austin Museum of Digital Art (AMODA) is seeking volunteers "in a variety of roles." http://www.amoda.org

"The Future of Design "Core77's Design Competition: Over 700 designers from more than 60 countries are now registered to compete, with India and South America particularly well represented." http://www.core77.com/competition2002/default.asp

"WASHINGTON == Global warming caused by increasing manmade carbon dioxide in the atmosphere will lengthen the day, according to a study to be published this month by the journal, Geophysical Research Letters.

"Researchers at Belgiums Royal Observatory and the Catholic University of Louvain, Belgium, lead by Olivier de Viron, used computer models to analyze the effect of adding one percent more carbon dioxide to the atmosphere each year, in order to reach a doubling of the carbon dioxide concentration after 70 years.

"Scientists can currently measure the length of the day to an accuracy of about 10 microseconds (1/100,000 of a second). It fluctuates slightly, based primarily on changes in atmospheric winds and ocean currents, which affect Earth's angular momentum as it spins on its axis. Angular momentum measures the rotation of a non-rigid body, such as a planet, including its ability to continue to spin. As angular momentum is conserved, the solid Earth's rate of rotation is affected by the movement of its nonrigid components, the ocean and atmosphere.

"The Belgian scientists estimated the effect of the ocean and atmosphere, caused by increasing the amount of atmospheric carbon dioxide by one percent per year and its effect on global warming, on Earth's angular momentum. This rate of increase, they note, is a common scenario, based on current human activity. They used 14 different computer models, obtained from the Coupled Model Intercomparison Project, which showed reasonable agreement, they say.

"They find that the length of day would increase as a result of angular momentum changes associated with global warming, including variations in surface pressure over land masses, average surface pressure over the ocean, and zonal winds and currents, that is, those moving in an east-west or west-east direction. The amount of lengthening would be small, on the order of microseconds (millionths of a second) per year, and would be difficult to distinguish in any given year from naturally occurring variations.

"On a scale of decades or longer periods, though, the effect of global warming on the length of the day would be measurable, the researchers say. They anticipate an increase of around 11 microseconds (11/1,000,000 of a second) per decade in the 21st century, resulting in a total lengthening of the day by 0.11 (11/100,000 of a second) for the century as a whole."

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ELEVEN ONE-HUNDRED-THOUSANDTHS OF A SECOND
WOW, THAT'S LONG ENOUGH TO SEND EMAIL
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