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marshall
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16 Dec 2016, 4:58 pm

naturalplastic wrote:
marshall wrote:
"Polar Vortex" is actually misused in the media and even television meteorologists. The term originally describes a phenomenon in the stratosphere that occurs in winter over both poles of the earth. Sunlight typically warms the stratosphere as its absorption in the ultraviolet wavelength band is enhanced by the presence of ozone molecules. When the stratosphere falls dark above/below the arctic/antarctic circle, the stratosphere cools. This cool air slowly sinks causing a low pressure center above. Extremely strong winds often circle this area of low pressure, which is why it is called a vortex.

However, it's actually at times when the stratospheric polar vortex weakens and descends into the troposphere that cold air surges away from the poles at the surface. The breakdown of the stratospheric polar vortex in winter is usually what leads to cold outbreaks.


So what the media calls a "polar vortex" is really the opposite: a polar backed up toilet ?

Makes sense.

A vortex is a low pressure zone that causes fluid to flow into it in a spiraling pattern (like the water in a flushed toilet). The media dubs it a polar vortex when it gets backed up and spills outward. Hurricanes and tornadoes are both low pressure zones. And both look like the water in a flushing toilet. But the cold air coming down from Canada on American weather maps acts like water flowing outward from a commode because its from a high pressure zone.


This isn't exactly right. The difference is the stratospheric polar vortex fills and sinks very slowly compared to its rate of spin. The spin is more due to the spin of the earth deflecting winds to the right (coriolis effect) though, which is not the case in a toilet.

Also, in winter the high pressure is in the lower troposphere while the low pressure is in the stratosphere. Think of it like this: a column of cold air is comparatively thick on the bottom, but thin on the top. This is because cold air is more dense and settles into a thinner layer. To compensate for the thickness in the lower troposphere, the air must be thinner above (in order for the total weight of the air column to remain the same).



naturalplastic
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16 Dec 2016, 10:28 pm

They always claim that the toilet thing IS caused by the coreoulis effect.

Whatever..

The point is that though a hurricane IS a vortex at ground level( a low pressure zone the draws air in like a sink drain draws in water) a polar vortex is not a vortex on the ground. It is a high pressure zone that sends winds away from its center. We on the ground get the cold northern winds coming at us from the pole. So on the ground a polar vortex looks like the opposite of a "vortex" (opposite of how a drain works). Its only a "vortex" in the upper atmosphere. The low pressure is above the weather in the stratosphere/upper troposhere where it is low pressure, and where upper level air IS drawn in from the lower latitudes (before that air chills and sinks down into the lower atmosphere.



marshall
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17 Dec 2016, 10:17 am

naturalplastic wrote:
They always claim that the toilet thing IS caused by the coreoulis effect.

No, it's caused by the direction of the water jets and/or the shape of the bowl. The coriolis effect only operates on a large scale.

Quote:
The point is that though a hurricane IS a vortex at ground level( a low pressure zone the draws air in like a sink drain draws in water) a polar vortex is not a vortex on the ground. It is a high pressure zone that sends winds away from its center. We on the ground get the cold northern winds coming at us from the pole. So on the ground a polar vortex looks like the opposite of a "vortex" (opposite of how a drain works). Its only a "vortex" in the upper atmosphere. The low pressure is above the weather in the stratosphere/upper troposhere where it is low pressure, and where upper level air IS drawn in from the lower latitudes (before that air chills and sinks down into the lower atmosphere.

Yea, the polar vortex is the exact opposite of a hurricane. A hurricane is fueled by heating in the troposphere (via water condensation) whereas the polar vortex is driven by cooling in both the troposphere and stratosphere (via radiation to space). A hurricane is a surface-based low pressure anomaly, whereas the polar vortex is an upper level low pressure anomaly.

However, there are surface-based low-pressure systems that circle the outer edge of the polar vortex. These low-pressure centers develop as waves along the outer edge of the polar cold-pool, with warm fronts, cold fronts, and associated precipitation.

It requires some difficult math to prove, but the net effect of these waves of low pressure is to draw the westerly winds of the polar vortex downward and equator-ward over time. The lower part of the polar vortex can become unstable causing it to actually break into two or more sub-vortices. Usually these sub-vortices break off over the continents in the northern hemisphere. This phenomenon corresponds to prolonged cold-outbreaks over North America and Siberia. It is the tropospheric portion of the polar vortex that can break up.



androbot01
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17 Dec 2016, 11:17 am

It's bloody cold outside.
People have been advised to stay inside as frost bite will set in in minutes. The air is literally so cold it will burn your skin.
I was born in this climate and have spent 46 winters in it. I don't know if it is getting worse or if I am getting less patient. But I'm fed up with it.