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Tom Harbold: Weather patterns spawn new terms

A few years ago we learned about the existence of a weather formation called a derecho, defined as a widespread, long-lived, straight-line windstorm that is associated with a land-based, fast-moving band of severe thunderstorms. This year, we have two new meteorological terms to add to our lexicon: "polar vortex" and "bombogenesis."

As 2014 dawned, it brought with it a gift from the North Pole not brought by Santa Claus: a polar vortex, defined by CNN senior meteorologist Brandon Miller as the circulation of strong, upper-level winds that normally surround the northern pole in a counter clockwise direction, a polar low-pressure system.

These winds tend to keep the bitter cold air locked in the Arctic regions of the Northern Hemisphere. It is not a single storm, but a weather pattern characteristic of the polar region. On occasion, this vortex can become distorted and dip much farther south than you would normally find it, allowing cold air to spill southward. This is what happened early this month.

But wait, there's more. Last week we became the unwitting, and perhaps unwilling, recipients of "bombogenesis," a term meteorologists - who seem to be gifted word-smiths, as well as interpreters of atmospheric phenomenon - use to describe an area of low pressure that "deepens rapidly," creating a strong storm, or cyclone, that intensifies as it moves over the ocean, according to Bob Oravec, a National Weather Service forecaster quoted by NBC.

In order for a bombogenesis situation to develop, a cold air mass needs to meet a warmer one, as often happens during East Coast winters, when cold Arctic air meets the comparatively warm waters of the Gulf Stream off the coast. At that point the barometric pressure drops, sending the winds into overdrive; condensation clouds bring the snow or rain, and a storm, well, explodes over the area. Many of us were still shoveling out of the last detonation well into last week.

Needless to say, such dramatic fluctuations in the weather, especially coming on the heels of the last two years of relatively mild and snowless winters, have led to much speculation about what, if any, relation this has to global warming, or climate change as it is now usually called. Some argue that global warming models predicted an increase in erratic and violent weather as a result, which is true.

Others point to the fact that much less Arctic ice melted in the summer of 2013 than has the last several years, the fact of much less-active solar weather, and the fact that we're coming near the end of the average length of an interglacial period, and predict that we're headed into another Ice Age.

For myself, it's clear enough that we have been warming. The loss of glaciers worldwide and sea ice in the Arctic - at least until this year - are evidence enough of that. To what degree it's natural and to what degree anthropogenic, or human-caused, is the question, and it's a question to which I don't have an answer. Nor am I completely convinced that anyone does. If there is one thing we are learning, or ought to be, it's that weather and climate are much more complex and unpredictable than we had thought.

It's only common sense to take what reasonable steps we can to reduce our impact on this planet and its atmospheric, hydrologic and other systems. That's all the more true when the majority of such steps result in more pleasant living conditions for us humans. But I suspect that we have not seen the last of severe weather conditions, nor the creative names meteorologists come up with to describe them.

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