“A lot of the changes in the recent past have been due to air pollution,” Frierson said. A recent study by Frierson and collaborators looked at how pollution from the industrial revolution blocked sunlight to the Northern Hemisphere in the 1970s and ’80s and shifted tropical rains to the south. NASA Earth Observatoryįrierson’s earlier work shows how the changing temperature balance between hemispheres influences tropical rainfall. “This is really just another part of a big, growing body of evidence that’s come out in the last 10 or 15 years showing how important high latitudes are for other parts of the world,” Frierson said.Ī satellite picture of clouds shows a narrow band of intense rainfall, known as the inter-tropical convergence zone, just north of the equator. The slowdown of the currents is predicted because increasing rain and freshwater in the North Atlantic would make the water less dense and less prone to sinking.
#WETTER WASHINGTON MOVIE#
While a sudden shutdown like in the movie won’t happen, a gradual slowing – which the recent United Nations report said was “very likely” by 2100 – could shift tropical rains south, the study suggests, as it probably has in the past. The ocean current they found to be responsible was made famous in the 2004 movie “The Day After Tomorrow,” in which the premise was that the overturning circulation shut down and New York froze over. For such a major feature there’s usually a simpler explanation,” Frierson said. “But at the same time, a lot of people didn’t really believe that explanation because it’s kind of a complicated argument.
“It rains more in the Northern Hemisphere because it’s warmer,” said corresponding author Dargan Frierson, a UW associate professor of atmospheric sciences. In general, hotter places are wetter because hot air rises and moisture precipitates out. 20 in Nature Geoscience, explain a fundamental feature of the planet’s climate, and show that icy waters affect seasonal rains that are crucial for growing crops in such places as Africa’s Sahel region and southern India. But a new University of Washington study shows that the pattern arises from ocean currents originating from the poles, thousands of miles away. Scientists long believed that this was a quirk of the Earth’s geometry – that the ocean basins tilting diagonally while the planet spins pushed tropical rain bands north of the equator. The Palmyra Atoll, at 6 degrees north, gets 175 inches of rain a year, while an equal distance on the opposite side of the equator gets only 45 inches. A quick glance at a world precipitation map shows that most tropical rain falls in the Northern Hemisphere.
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