atmospheric pressure in tornadoes

[kangaroota]

We know that a tornado is the ultimate 'deep depression' but does anyone know what the actual barometric pressure falls to inside a twister?

[zerozero]

Google is a wonderful thing (http://ams.confex.com/ams/pdfpapers/74267.pdf)

I just skimmed the document but it seems to be about 900 millibars.

???

[Engineer]

It is one flying experience I do not want to comment on :D

[speed freek]

it seems to be about 900 millibars

Zerozero, any chance for a link to that document. Considering that normal ISA barometric pressure at the surface is 1013.2 mb, then if its measured at 900 mb, well....thats not really much more than a wind really (albeit a strong wind). I remember from MET in flight school as the eye of a tornado being measured at 2 mb. Hence the video footage of houses being instantly pummeled when the tornado hits them.

Cheers.

[Groundloop]

Wind speed is not just a question of difference in pressure but also pressure gradient. Therefore a drop of 100mb over only a hundred metres or so will produce one h*ll of a wind!


2mb seems rather unbelievable.

[MeatHunter]

2mb

That would be very close to an absolute vacuum. In theory this is possible but unable to be acheived on this planet

[speed freek]

sorry fellas. Maybe its 200mbs. I do remember a two being in there.

[zerozero]

Speedfreak, I did make a link to the document but I was being sarcastic (sorry) when I titled it "Google is a wonderful thing."

Just click on that one.

[Old Smokey]

kangaroota,

My old Met text book records the lowest ever recorded pressure as 882 hPa (26.05" Hg). That text book was produced in 1964, and later record lows may exist.

MeatHunter,

Absolute vacuum unachievable on this planet ? Take a look at the various Government legaslative assemblies. That's about as close as you can get to an absolute intellectual vacuum. But then, politicians may not be from this planet.....

[readbackcorrect]

yeah 900mb for a hurricane but a tornado ??

[minus273]

Hey there,

I found this page, not sure how good it is, but says 800mb for a tornado.

http://www.physicalgeography.net/fundamentals/7t.html


-273

[PaperTiger]

The generally estimated pressure drop inside a tornado ranges up to 200mb depending of the ferocity (F number). 100mb is the highest ever recorded although larger tornadoes may be expected to show larger diferences. The ambient pressure around tornadoes is likely to be less than the standard 1013mb, so an actual reading of ~800mb is theoretically possible.

The notion of objects 'imploding' due to vacuum is a myth, as is the opening of windows to relieve the pressure. The damage is done by the wind and vortex.