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Every Second Counts

Geophysicists Blame La Nina Weather for Lost Time

January 1, 2008

Geophysicists have identified the very real physical mechanism that can lengthen or shorten the amount of time the earth takes to complete one rotation. During La Nina the temperature of the Pacific Ocean cools, which causes the jet stream to slow down. The principle of angular momentum requires that something must adjust to make up for the change in energy, thus the earth spins faster to compensate. This means that it takes less time to complete one day – but the difference is no more than a millisecond each day. A change this small can still be enough to impact precise navigation measurements.

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Science Insider

ABOUT EL NINO: El Niño is a cyclical warming of the ocean waters in the central and eastern tropical Pacific that generally occurs every three to seven years, usually around the holidays. It is associated with changes in air pressure and the movement of high-level winds, and can affect weather worldwide. In the United States, En Niño normally results in warmer-than-normal temperatures across the northern and western states. Wetter conditions result in the south, with dry weather across the Ohio Valley and Pacific Northwest. El Niño typically peaks during the winter months. It alternates with La Niña, the cooling of ocean waters in the same region of the Pacific.

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TO GO INSIDE THIS SCIENCE:
Dr. Jean O. Dickey
Physicist
Jet Propulsion Laboratory
Pasadena, CA 91109-8099
818-354-3235
jean.o.dickey@jpl.nasa.gov