What are big storms like the one that hit the East Coast called nor’easters? My husband says it’s because they usually hit the northeast part of the country.
He’s wrong, but then knowing him as you no doubt do, this probably doesn’t come as a big surprise, does it?
A nor’easter – northeaster – is so named because of the direction of its winds.
A nor’easter often is formed by a cold storm that has moved though the Ohio Valley or Gulf states and then moves out over the Atlantic. When it does so, it picks up new strength from the warm ocean water.
The warm air rises and the cold air sinks and that creates a lot of instability in the upper atmosphere and an area of low pressure below.
The Earth’s rotation sets the storm spinning in a counterclockwise direction, hence the northeast winds, and typically it goes spinning up along the Atlantic Coast. That path means it is always sucking in more warm ocean air and water that combine with the colder air on land to keep the storm fueled.
As incoming air rises around the center of the storm, it gets carried off by the jet stream and that increases the speed of the incoming air. The faster the air moves, the faster the barometric pressure drops. In a really severe nor’easter, the pressure can drop 24 millibars in 24 hours. This is known as a “bomb cyclone.”
Nor’easters generally don’t have wind speeds as high as those in a hurricane, but they can last a long time – up to a week – before they finally blow themselves out.
People used to believe storms came from the direction of the winds. In other words, if the winds blew from the southwest, they thought that’s where the storm came from.
Benjamin Franklin never quite figured out the whole spin of the winds thing, but he began to suspect something was going on when a nor’easter hit Philadelphia and blocked his view of an eclipse. He later found out people in Boston saw the eclipse before the same storm hit there.
So he reasoned that even though the storm winds were from the northeast, the storm had started to the south.
*Clay Thompson writes for The Arizona Republic. You can read his column by going to http://www.azcentral.com