What causes the Azores high?

hatrickpatrick

This might sound appalling to some of you, coming from a guy who's always been interested in weather and climate, but I only discovered the Azores high this summer Obviously I'd heard of the Azores before, but I only recently found out that it had a more or less permanent area of high pressure.

I have to admit that this overturned a lot of perceptions I used to have about weather patterns. I've always known that there are patterns, such as tropical waves and cyclones generally moving in an anticlockwise loop, west towards the United States and then generally curving east back into the Atlantic, and the El Nino / La Nina oscillation. But the concept of a permanent area of high or low pressure over a certain geographic location is totally new to me, I always assumed that cyclones and anticyclones were constantly in flux. Perhaps that perception comes from growing up in a country which has a different climate one hour after another!

So my question is, what causes this particular area of high pressure? Why is it always there, and why does it affect the movements of other weather systems around it rather than vice versa?
I checked the Wikipedia article but it has almost nothing on the actual mechanism which causes an area of high pressure to remain static in the same place like that. Had a quick Google for information, but most answers state that it is indeed there, but don't go into why.

Anyone know about this? Or could direct me to a decent explanation of it?

Sorry if this seems like a newb question, as I said I've always been interested in what causes the weather but I guess you learn something new every day!

Su Campu

The Azores high is just one of the semi permanent high pressure zones that are found at around 30 N and S of the Equator. There is nothing unusual about it and it has always been there.

Hot air near the Equator rises and travels poleward, and subsides at around 30 degrees latitude. This subsidence causes high pressure at the surface and usually dry or arid climate. This is why the major deserts of the world are found around these latitudes.

The tropical storms actually follow a clockwise path around the high pressure zones. They usually form to the south of the Azores or Bermuda high and are steered westwards and then north and northeastwards around them.

hatrickpatrick

Su Campu wrote: »

The Azores high is just one of the semi permanent high pressure zones that are found at around 30 N and S of the Equator. There is nothing unusual about it and it has always been there.

Hot air near the Equator rises and travels poleward, and subsides at around 30 degrees latitude. This subsidence causes high pressure at the surface and usually dry or arid climate. This is why the major deserts of the world are found around these latitudes.

The tropical storms actually follow a clockwise path around the high pressure zones. They usually form to the south of the Azores or Bermuda high and are steered westwards and then north and northeastwards around them.

Right thanks, that clears up a lot. What I'm basically wondering is why it's permanent while other pressure areas move around.
To narrow the question a bit, is there any particular reason the hot air settles at 30 degrees L, instead of just continuing towards the poles?

Su Campu

hatrickpatrick wrote: »

Right thanks, that clears up a lot. What I'm basically wondering is why it's permanent while other pressure areas move around.
To narrow the question a bit, is there any particular reason the hot air settles at 30 degrees L, instead of just continuing towards the poles?

It's all to do with the conservation of angular momentum in relation to the Hadley and Ferrel Cells. This will explain it all.

http://en.wikipedia.org/wiki/Hadley_cell