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Originally Posted by MAXUM
Thank goodness for "global warming", sounds like we are in for some downright balmy weather!
So I'm really curious as to why during the winter time we tend to be affected by storms and weather that originate in Canada or Alaska (as in this case) where not so much in the summer time? I know much of that has to do with the jet stream(s), but I never did get why thier placement and flow seems to different between summer and winter. Or is my observation completely wrong?
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The jet stream is the key. First, the definition of the jet stream:
The jet stream marks the boundary between cold arctic air to the north and warm tropical air to the south. The jet stream's strength depends on the temperature difference between these two air masses. The jet stream is strongest during the winter, when the temperature difference is greatest.
So, in the winter, you have two factors contributing to the Canadian storms: (1) Strength of the jet stream, and (2) Position of the jet stream.
Strength - Since the temperature at the equator is constant, the cold Canadian air during winter increases the temperature difference, thereby strengthing the jet stream.
Position - The jet stream is over Canada and Alaska in the summer; moving South over the northern U.S. and southern Canada during the winter, as the cold air boundary expands.
So, since cold air is heavy, and the jet stream is strong and directly over us in the winter, it creates a "funnel" of sorts, periodically drawing chunks of real cold air from Alaska and Canada. When this cold air hits the warm air (along the jet stream), big storms form.
That's it in a nutshell.