storm

[george013]

When wind is blowing on a subject, you will get a overpressure on that site and an underpressure on the other site. A few weeks ago that was nicely vissible with a storm and this chimney. It's clear to see that the smoke is sucked back due to the underpressure.



Next picture is under a more normal weather situation.



George

[jcuknz]

Interesting effect .. I didn't know that

[IzzieK]

Me too...I am not a techie on smokes at all but I like the textures generated by these monsters...

[george013]

It's like with many things: if you don't know it, you don't see it, and if you know it, you see it. It's like learning photography.

A day before I drove just to the chimney and straight in the wind. Two flows of clouds where visible behind the chimney seperated by a line. Thanks to the sun. No camera with me.

George

[IzzieK]

Just curious, George...are you an industrial engineer?

[george013]

Just curious, George...are you an industrial engineer?

No, and no gardener either.





Central heating.

George

[Manfred M]

When wind is blowing on a subject, you will get a overpressure on that site and an underpressure on the other site.

Good catch, George.

Exactly the same principle that lets airplanes fly. The shape of the wing creates a low pressure area above the wing and a high pressure area below it and voila, a heavier than air object can fly.

On the downside, this is also what happens during a tropical storm, when high winds on one side of a building creates a high pressure zone and on the opposite side, a low pressure area. If there is a small pressure differential, the windows get blown out. If the pressure differential is high, the walls get blown out and the building will collapse.