A pinwheel-like pattern of high pressure clouds stretches across the eastern United States at 3:05 PM Eastern Daylight Time (19:05 UTC)on September 23, 2010. At that time the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Aqua satellite passed overhead and captured this true-color image. The high pressure weather system that brought fair weather and relatively clear skies to the United States also created this atmospheric art.

The circular pattern to the clouds—stretching from Ohio to Florida and from Arkansas to the Atlantic Coast—was caused by the flow of air around a sprawling high-pressure ridge centered in western Virginia, North Carolina, and eastern Tennessee. In meteorology, high pressure ridges form where air is sinking from high altitudes toward Earth's surface. The descending air flows out from the center in clockwise spirals in the northern hemisphere and counter-clockwise in the southern hemisphere.

Credit: Jeff Schmaltz, MODIS Land Rapid Response Team, NASA GSFC Click to enlarge.

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