# Hurricane Bonnie

 The power of hurricanes The power carried by the air moving past a fixed point is proportional to the cube of the wind's velocity.  Hurricane Bonnie evidently had winds of 110 miles per hour, and moved at 20 miles per hour.  For simplicity, let us assume that the hurricane moved due west. On the north side of the hurricane, the wind moved at 130 (= 110 + 20)  on the south, at 90 (= 110 - 20) mph, owing to the counter-clockwise circulation of the winds.  The power of the wind on the north side was (130/90) cubed = 3 times as great as that on the south.  (When the famous 1938 hurricane hit New England, traveling north, the fate of people depended very much on whether they were on the east (high velocity side) or the west (low velocity side) of the eye of the hurricane. Let us imagine a hypothetical excellent windmill of 10-meter diameter in such a wind (130 mph = 58 meters per second).  In those ferocious winds, it could produce (see  Windmills ) about 5 MW of power, about 1/200 of the power output of a large electrical power plant (nuclear, coal, natural gas). That same windmill, were it to survive the hurricane, would produce about 3 kW in the more normal 5 m/s wind, a mere 0.06% of its power in the hurricane(and three-millionths of the power of a serious power plant).  Alternatively, this hypothetical windmill, producing a little power in 5 m/s winds)has to be overdesigned by a factor of about 1600 to be able to operate safely in the hurricane. (It's like having an engine from a Mack Truck on a lawn mower "just in case.)