9-16 January 2011 - N. American Surface Temperature Anomalies - EO/NASA

[hatrack]

Snow fell in the U.S. Deep South, severe storms battered the East Coast, and International Falls, Minnesota, set a new temperature record: -46 degrees Fahrenheit (-43 degrees Celsius) on January 21. But in areas north of the United States and southern Canada, temperatures were above normal. In fact, unusual warmth forced residents of Iqaluit, capital of the Canadian territory of Nunavut, to cancel their New Year’s snowmobile parade.

This map of the United States, Canada, eastern Siberia, and Greenland shows temperature anomalies for January 9 to 16, 2011, compared to the same dates from 2003 through 2010. The anomalies are based on land surface temperatures observed by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite. Areas with above-average temperatures appear in red and orange, and areas with below-average temperatures appear in shades of blue. Oceans, lakes, and areas with insufficient data (usually because of persistent clouds) appear in gray.

Because this image shows temperature anomalies rather than absolute temperatures, red or orange areas are not necessarily warmer than blue areas. The reds and blues indicate local temperatures that are warmer or colder than the norm for that particular area. The overall configuration of warmer-than-normal temperatures in the north and cooler-than-normal temperatures in the south probably results from a climate pattern known as the Arctic Oscillation (AO).

The AO is a pattern of differences in air pressure between the Arctic and mid-latitudes. When the AO is in “positive” phase, air pressure over the Arctic is low, pressure over the mid-latitudes is high, and prevailing winds confine extremely cold air to the Arctic. But when the AO is in “negative” phase, the pressure gradient weakens. The air pressure over the Arctic is not quite so low, and air pressure at mid-latitudes is not as high. In this negative phase, the AO enables Arctic air to slide south and warm air to slip north. The AO went into negative phase in the Northern Hemisphere winter of 2009–2010. The AO was in negative mode again in the winter of 2010–2011, affecting temperatures across the Northern Hemisphere as early as December 2010.

EDIT

http://earthobservatory.nasa.gov/IOTD/view.php?id=48882

[xchrom]

1. recommend

[loudsue]

2. I wonder if, in addition to climate change due to carbon burning, this could be from the tilt

of the earth's axis. It is supposedly doing its little wobble thingy.

[happyslug]

3. The best story I have read deals with the refreezing of the arctic in the Winter

Now, about September 23rd of each year the Arctic Ice Sheet is at its minimum, after the first day of Autumn, the ice starts to spread, by Christmas most of the Arctic has returned to ice coverage.

Now, when water turns from Water to ice, it releases heat. This "Hot" air has to go somewhere given the warmer the air the larger the air molecules are. This "Hot Air" (Probably around 32 degree Fahrenheit, that is hot for the Arctic) then pushes south over the landscapes of North American. Greenland and Siberia. This pushes the cold air that is from the cold land masses further south and this continues till it hits the tropics. In affect everyone is getting the weather of about 100-200 miles to their north EXCEPT the far north which is having a warmer then normal winter (Through still below refreezing).

This explains the lack of Snow during last years Winter Olympics and the lack of snow in Northern Canada this year and also explains the increase snow in the Northern US (Most years this snow would have come down as rain, but do to the Colder temperatures it is coming down as snow).

It is the best explanation I have heard, I can NOT vouch for its accuracy but it does tie in with global warming i.e. in previous years the Arctic NEVER was a source of "heat" for its ice stayed Ice all year round and thus no general push to the south of cold temperatures. Yes, Global warming can lead to colder and more severe winters. That was commented on 30 years ago when Global Warming started to hit the popular press. Global Warming is not only a general warming, but a switch to a greater change in temperatures throughout the year.

[muriel_volestrangler]

4. It's not doing any 'wobble' that it hasn't done for millions of years

And that change in axial tilt is part of what causes the Ice Age cycles - and the next change due in that is for a new glacial period to start, not a further warming.

[Dogmudgeon]

5. Look up "Milankovitch Cycles"

I'd post a link, but if you go to Google, you'll get literally thousands.

However, they don't drive quick climate changes. They change in time periods of tens of thousands of years.

--d!