Robb Ellis, meteorologist at WECT and WSFX. (Photo courtesy WECT)
Hurricanes do tend to accelerate as they move into higher latitudes (that is to say, farther north). The reason why consists of two main influences.
The first influence is that of the jet stream and any associated troughs that tend to steer tropical systems as they move north. Winds with these systems can move exceptionally fast in the upper levels of the atmosphere, helping to accelerate the storms as the system gets caught up in the larger flow or the mid-latitudes.
The more complicated part to this acceleration involves the conservation of angular momentum. Because a tropical system has a certain rotational speed, the laws of physics demand that it conserve that momentum. The Earth spins at a certain speed, but as you move to higher latitudes the speed required to make a full revolution is lower. Think of it as the kids on a merry-go-round. If you stand closer to the center of the merry-go-round, your speed is closer to zero. But as you move to the edge of the merry-go-round, your speed is faster. That momentum has to be conserved. The result is that in order to conserve angular momentum as a storm moves north, a resultant acceleration (generally to the east) compensates.
Robb Ellis is a meteorologist with television stations WECT and WSFX in Wilmington.
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Date posted: September 21, 2010
User-contributed question by:
Jim O'Connor
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