How was North America divided?

America is divided into two weather extremes

Red and blue

The United States is divided into two parts: red and blue states. For once, this has nothing to do with politics and the colors of the Democrats and Republicans. Because the border between the two colors runs roughly along the Rocky Mountains - and separates a large east with sometimes extreme minus degrees from a smaller west, whose winter has so far been significantly too warm. California, for example, was hit by huge forest and bush fires before Christmas 2017, driven by strong winds, drought, unusual for the time of year, and high temperatures. On the other hand, the US Northeast (and large parts of Canada) froze in partly arctic conditions: In some cases it was more than 15 degrees Celsius colder than the long-term average. The map does not show absolute temperatures, but how much they deviated from the usual average between December 26, 2017 and January 2, 2018 - the more intense, the darker the blue or red shade. This blatant dichotomy is caused by the course of the jet stream over the continent. It swings strongly to the north in the west and allows warm air masses to penetrate far north, so that even in Alaska it is too warm for the time of year. East of the Rocky Mountains, on the other hand, the jet stream strikes far south - and carries extremely cold air from the snow-covered expanses of Canada to the Gulf of Mexico.

This article is included in Spectrum - The Week 01/2018