One of my goals is to learn about things we hear about all the time for which I know very little about. In addition to general self improvement I can also look smarter around my children when they ask difficult questions! New England just experienced a very significant Nor’easter now infamously known as the Halloween Nor’eatser. What exactly is a Nor’easter? I know it’s a big winter storm but that’s as much as I know. So off I go to Wikipedia and Google definitions to get an education.
Here is what I learned…
A Nor’easter is a large scale and long duration counter clockwise rotating storm that travels up the North American east coast with strong cold winds, rain or snow, and high seas. A Nor’easter is similar to a hurricane in that they both have counter clockwise cyclonic winds, cause precipitation and winds, and both travel up the east coast. There are some differences for instance hurricanes are named and Nor’easters are not. Also Nor’easters are associated with winter and have cold-cores and hurricanes with summer and have warm cores. Hurricanes have winds between 74-130 mph while Nor’easter winds generally have gale-force winds between 39-54 mph. Nor’easter can last for days while hurricanes pass in hours. Even with weaker winds and no name to give them importance Nor’easter can produce significant damage like down trees, coastal flooding and erosion, record snow falls, and cold related deaths.
What causes a Nor’easter?
The storm usually begins in the Gulf of Mexico where warm moist air pools. The warm air rises, creates a vacuum or low pressure, and the cold air rushes in causing more warm air to rise and more cold air in, all the while picking up speed. Where does the cold air come from? The Arctic oscillation which is a cold air stream that is usually moving easterly around the earth so fast it acts as a dam but when it occasionally slows down it can more easily be interrupted and react with warmer air and begin to cool the jet stream crossing US.
The storm then begins to move east with the jet stream (which is also pulling the warm air up and increasing its intensity) and because of the Coriolis Force. What is the Coriolis Force? It is when objects or masses deflect to the right (in the northern hemisphere) because of the earth’s rotation. This is like inertia or when you take a left turn in your car and your body pulls to the right. What are jet streams? Jet streams are relatively narrow bands of flowing air that general meanders from west to east because of the earth’s rotation. They also includes perpendicular spirals of warm air rising and cool air falling. Once the storm hits the Gulf Stream it begins to move north along the coast and feed on its warm waters. The storm will continue up and grow in intensity as it meets up with the Labrador current (which is a cold water current that flows down from the arctic along the Canadian landmass) hitting the coast anywhere from about Virginia through New England on up to Canada.
Now you know
Well it wasn’t easy getting here but it is finally starting to make sense to me. I hope it is also a little clearer for you. It has also made me even more aware of how little I know. So maybe this will be an initial installment in a series about storms or weather or a multitude of other complicated scientific systems.
In the mean time keep safe and warm and I hope the 2011 Halloween Nor’easter hasn’t affected you too adversely!