into the lower latitudes where it eventually warms again under the strong tropical sunshine.

The circulation patterns of the atmosphere and the oceans are relatively stable on a large scale

and over long periods of time.  However, year to year variations in temperature can result in fluctuations of the global pattern that in turn cause fluctuations in climate.  This will vary the weather patterns from season to season.  But as long

as the sun shines and the earth spins, the wind and waters will blow and flow to modify temperature extremes from north to south.       

By: Mark Bloomer

Many weather phenomena are created and guided by powerful ribbons of wind high in the atmosphere. The largest of these is  known as the "jet stream", named for the early jet airplanes that discovered this river of fast moving air.

In our latitude, jet stream winds flow from west to east, and are usually most intense where temperatures contrast steeply between cold air to the north and warm air to the south.  The jet stream across North America is commonly focused in two branches.  The northern branch of the jet stream borders arctic air to the north from polar continental air to the south and usually flows from west to east across southern Canada.  The southern branch of the jet stream borders continental polar air to the north from subtropical air to the south.  This branch usually flows across the southern United States.

Many of our storm systems begin to form as a wave propagates along the jet stream.  This wave can be compared to an ocean wave, or a wave rippling along a rope that's been shaken at one end.  Waves in the jet stream originate in many ways.  Wind flow over mountains, the remnants of tropical storm systems, and cold fronts can all initiate waves in the westerlies.  Many of the jet stream waves that develop into east coast storms originate in the Pacific.  A cold air mass breaking south from the Arctic region and colliding with warmer Pacific air in the gulf of Alaska can create a pulse of in