National Geographic : 1975 Dec
"The wind is awake," wrote poet John Cheney, and indeed it is; nearly always, nearly every where. But wind power-the amount of energy available in the breezes-depends not so much on the average wind speeds as on the hourly dis tribution of winds, on terrain and obstacles, and on altitude. As the darkest tints indicate, the New England coast, the western Great Plains, and the Pacific Northwest offer the contiguous United States' greatest wind energy potential, largely because of powerful winds that occur part of the time. That's impor tant, for wind power increases as the cube of wind velocity. In other words, a little more wind means a lot more power. An example: Assume that the wind in Chicago blows con- stantly at its average speed of 11.2 miles per hour, but that the average for Minneapolis, also 11.2 mph, comes from winds that blow 8.2 mph for half of each day and 14.2 mph for the other half. Because of the cube factor, the city of Minneap olis would have available during its windier half day as much energy as Chicago would have during the whole day. 819 ial ,ed\ ^--^~^- :s ^. £?