Jet stream

[phantom power]

Rossby wvaves, bitches.

The chaotic flow of the air in the polar vortex sometimes allows a large dip (a sharp trough of low pressure) to form in the jet stream over North America, allowing the Arctic air that had been steadily cooling in the northern reaches of Canada in areas with 24-hour darkness to spill southwards deep into the United States. In theory, the 1.5°F increase in global surface temperatures that Earth has experienced since 1880 due to global warming should reduce the frequency of 1-in-20 year extreme cold weather events like the current one. However, it is possible that climate change could alter jet stream circulation patterns in a way that could increase the incidence of unusual jet stream "kinks" that allow cold air to spill southwards over the Eastern U.S., a topic I have blogged about extensively, and plan to say more about later this week.

http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=2605


Figure 4. From wunderground's Jet Stream page, we see the large dip in the jet stream over the U.S. responsible for this week's extreme Arctic air outbreak.

[kristopher]

1. After it loads step it from 1000 thru 70 hPa

Posted yesterday on GD: http://www.democraticunderground.com/10024287755

Polar vortex
From Wikipedia, the free encyclopedia
Polar vortex over Maine on the morning of January 21, 1985
A polar vortex (also known as mignogno cyclones, polar vortices, Arctic cyclones, sub-polar cyclones, and the circumpolar whirl) is a persistent, large-scale cyclone located near one or both of a planet's geographical poles. On Earth, the polar vortices are located in the middle and upper troposphere and the stratosphere. They surround the polar highs and lie in the wake of the polar front. These cold-core low-pressure areas strengthen in the winter and weaken in the summer.[1] They usually span 1,000–2,000 kilometers (620–1,240 miles) in which the air is circulating in a counter-clockwise fashion (in the northern hemisphere). The reason for the rotation is the same as any other cyclone, the Coriolis effect.

The Arctic vortex has two centres, one near Baffin Island and the other over northeast Siberia. In the southern hemisphere, it tends to be located near the edge of the Ross ice shelf near 160 west longitude....

Play with it between 18,000 to 58,000 feet. Using the different types of maps under the selection "projections" adds perspective.

Go to: http://earth.nullschool.net/

Click the word EARTH in the lower left corner for the control panel.

"hPa" is a measure of air pressure; the higher the number the lower the altitude.

1005 hPa at 226ft is about the height of the nacelle of a new large wind turbine, so the 1000 setting (364ft) is the best proxy.

10 hPa is about 85000ft

070 +- 58,000ft
250 +- 34,000ft
500 +- 18,000ft
700 +- 10,000ft
850 +- 5,000ft

Projection determines the type of map displayed.

Control shifts forward or back in time from present.

Clicking on the map gives location coordinates and wind speed.

Data is refreshed every 3 hours I believe.

[phantom power]

2. that is a shiny display