4.3 Global Warming and the Polar Vortex
Cold air is heavier than hot air. The air at the poles is very cold, The air at the equator is very hot. What would we expect if we had cold air next to warm air? Since the cold air is heavier we'd expect it to spread out underneath the hot air. Likewise we'd expect the hot air to spread out on top of the cold air. When the hot air moves up and spreads out it is wind. So if we are in the northern hemisphere near the north pole we expect wind near the ground to blow southward toward the equator. We expect hot air at the equator to rise up and spread northward. The colder the polar air is the heavier it is and the more it presses downward and southward. The hotter the air at the equator is, the lighter it is and the more it presses upward and northward. The movement of air between the pole and the equator is called the Hadley cell. The speed of the winds depends on the temperature difference between the Artic and the Equator. The bigger the difference the faster the speed.
This is shown in the diagram below that comes from weather.gov . The Hadley cell is drawn in blue and red. Blue stands for cold and red stands for hot. Air that moves south gets hotter the closer to the equator it gets. That's why the diagram shows it blue near the pole and red near the equator. Once it's red it rises up as shown in the diagram and flows back to the pole where it becomes colder and the line becomes blue again.
What happens is more complicated than this. To understand one reason for this it is necessary to understand the Coriolis effect. There is a great video explaining this on the National Geographic Web Site that is embedded below.
What would we expect would happen over the equator? There should be no Coriolis effect. A great experiment showing this is in the video below in which they put a sink directly over the equator.
With a sink the water goes down. In the case of a hurricane the air goes in at the bottom, up in the center and then outward at the top. The center is a low pressure area. What would happen if there was a high pressure area in the center? That does happen and it can create an anti-cyclone in which air goes down in the center.
The Coriolis effect causes air flowing to the poles and away from the poles to follow a curved path. This curved path doesn't reach all the way from the poles to the equator. As a result you get more than one cycle of air as shown in the picture below. Instead of one cell or cycle of air you get three of them.. Over the north pole there is the polar cell (3 in the diagram below from weather.gov). South of the polar cel is the Ferel cell (2). South of that is the Hadley cell (1).
There are also three cells of wind in the southern hemisphere. The speed of the vortexes in the cells gets higher the higher the temperature difference between the northern and southern sides of the cells.
Notice how where cycles 1 and 2 meet the air is coming down but where cycles 2 and 3 meet the air is going up. When the air is coming down it's a high pressure area and when air is going up it's a low pressure area. When air goes up it takes moisture up with it which condenses as rain. That's why the region between 2 and 3 gets a lot of rain. When air comes down it is usually dry which is why there are a lot of deserts at the junction of cycles 1 and 2.
Things are even more complicated than that because not only are the winds circulating up and down they are also circulating because of the Coriolis effect. The red arrows in the figure above show that.
The figure above has yellow lines. That is where the cells of circulating winds meet. A fast stream of wind that goes around the earth forms between the Polar cell and the Ferel cell and betweeen the Ferel cell and the Hadley cell. You can see them in the figure below also from weather.gov. Jet streams are very fast. On average they travel at 110 mph. In winter they speed up because the difference in temperature between the equator and the pole increases. Then they can reach speeds up to 275 mph. Why is there no jet stream formed over the equator? Hint, which way would it blow?
Jet streams are between 5 and 9 miles above the earths surface.
Here is a short video about the jetstream.
Scientists have named different regions of the atmosphere based on their height about the surface of the earth. You can see the names of those regions in the picture below.
Jet streams are in the troposphere. 10 to 30 miles above the surface in the stratosphere there is another circulating wind called the polar vortex.
Here is an awesome video from Stanford University of wind patterns on the earth. You can see that other than the jet streams and the polar vortex the other vortices don't go around the earth.
Here's another one.
Polar air that cools creates a low pressure by contracting and sinking due increased density. It's higher density creates high pressure which causes the cold air to spread southwards. According to articles I've read the winds of polar vortices act like a wall that reduces the flow of cold Artic air southwards. If the center of the polar vortex were to heat up the cold air over the poles would expand, the vortex winds would slow down and weaken and and more cold air would be able to move southward. This can push jetstreams southward that also separate cold and warm air. I've noticed that some articles call both the circulating winds in the stratosphere and the jet stream in the troposphere polar vortices while others just call the circulating winds in the stratosphere the polar vortex. For the sake of clarity on this page I refer only to the one in the stratosphere as the polar vortex.
When winter in places like the United States becomes very cold there are climate scientists who say that's because the Artic got warmer and slowed down the polar vortex. They say slowing down the polar vortex weakens it and lets Artic air pour into the United States.
What would happen if instead of the Artic getting warmer the air around the Artic got colder? The polar vortex would also slow down because the temperature difference went down between the air outside it and inside it. So polar vortex changes don't necessarily mean that the Artic got warmer.
It's important to point out that there are other reasons that the U.S. could get cold that have nothing to do with the polar vortex.
I am suspicous of any argument that says that global warming causes cooling. It sounds like an excuse made by global warming alarmists for when their predictions of heat don't come to pass.
What if I was a global cooling alarmist who warned everyone that the earth is getting colder and we are about to be covered with snow and ice? What if after I said that, the weather was very hot. I could say it's because of the polar vortex. I could say that the Artic was cooling and speeding up the polar vortex so less cold air was able to flow southward and that's why it's so hot. Obviously there is something wrong with these arguments.
In order for the polar vortex hypothesis of global warming to be correct the Artic has to be getting warmer and the Artic ice has to be melting. There are reports that this is true, however it is hard to know if these reports can be trusted and it is clear from the video below that predictions of the Artic being ice free by now have not come to pass.
Tony Heller has a video about the Artic ice in the two videos below.
Tony Heller discusses more predictions that went wrong in two videos below.
There are scary temperature graphs and graphs of shrinking ice on the web. Unfortunately because of politics involved and people who want us to be scared of global warming we can't trust the graphs produced by climate alarmists.
Ships that went to evaluate the change in ice at the Artic and Antartica got stuck in ice in both places and the people on board had to be rescued.
The earth has gone through warming and cooling periods throughout it's history because of changes in the earth's orbit and tilt toward the sun. Long before the industrial revolution that started in 1750 the earth has been warming and then cooling and then warming again as we can see from the lower blue line in the graph below that shows an estimate of temperature for the last 800,000 years. Notice how in 1950 the carbon dioxide is shown to have shot up in the upper graph. The temperature, in the lower graph though is still lower than it was 100,000 years ago. Doubling carbon dioxide doesn't appear to have significantly affected earths temperature.
Tony Heller speaks about the problem with the polar vortex arguments in the video below.
Click Here to Take Quiz and Earn Points
What About sea level rise? Isn't that proof of global warming?