14 March 2015

A different red-blue split in the U.S.

"This map produced by NOAA shows the land-surface temperature anomaly: how the temperature deviated from normal, on average, over the month. The darkest red areas were 12 degrees Celsius (22 degrees Fahrenheit) above average, while the darkest blue areas were 12 degrees Celsius below average."
The thermal anomalies are the result of a deeper jet stream curvature, the genesis of which is explained as follows:
The jet stream is generated by a combination of Earth’s rotation and the flow of air down atmospheric gradients between high-pressure, mid-latitude warmth and low-pressure Arctic cold. Over the last several decades, the Arctic has warmed faster than any other region; during periods of especially heightened warming, as occurs when melting sea ice exposes dark, sunlight-absorbing waters, the north-to-south temperature difference shrinks. The pressure differences flatten.

This decreased gradient slows down the jet stream—and as it slows, it also seems to become wavier, plunging south or veering north when encountering atmospheric obstacles it would once have coursed straight through. “The best analogy is to think of a river. When it’s flowing down a steep mountainside, it flows fast and straight,” says Francis. “When it gets to the coastal plain where there’s little slope to the land, it flows slowly and is easily deflected from its path.”

1 comment:

  1. Hmmm.

    - - First, I would point out that this is only a single month out of 12 for the past year and one out of many since such images have been made. So one can only draw partial conclusions by looking at this - even looking at it carefully. Nevertheless, it is interesting, isn't it?

    - - (NOTE: Be aware of the type of projection of this map, which is similar to Mercator, which greatly increases areas - artificially - the closer it goes to the poles. The increase is mainly due to east-west stretching. Canada including the islands shown is actually slightly smaller than the continental USA.)

    - - Note how much larger the blue shaded areas are than the red areas.

    - - In the continental USA blue-vs-red appears to be about a 50-50 split. In times like month this it is hard to convince people in the US northeast that global warming is real. And easy for people in the western states to agree with the idea.

    - - It appears that the deepest blue areas and deepest red areas are roughly the same size, not counting the Canadian Arctic islands, which tilt the deepest blue totals by quite a bit.

    - - Contrary to most of what we've heard, at least for this month the Arctic areas are colder than average. Most NOAA maps show the Arctic to be very warm.


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