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View Full Version : The answer my friend is blowin in the wind


The Munster
09-16-07, 09:36 AM
To all you theorists out there ..

Just read that if you open a window during a hurricane, it prevents your roof blowing off by equalising inside and outside air pressure.

Does anybody have a theory on this ? :hmm:

fatty
09-16-07, 09:39 AM
Are houses really that airtight that it would make a difference? I know my house has chimneys, attic vents, etc.

Tchocky
09-16-07, 09:43 AM
I'm not sure a chimney could cope with that kind of pressure differential.

*thinks*

kurtz
09-16-07, 09:51 AM
I would say, it would certainly help. Remember with the huge surface areas involved with houses a few psi can result in a couple of tons acting on a surface. in fact as an experiment try opening your front and back doors in a moderate breeze you should find one or other slams shut and takes a bit of a pull to open (assuming the winds in the right orientation w.r.t. the doors/

fatty
09-16-07, 09:55 AM
I'm not sure a chimney could cope with that kind of pressure differential.

*thinks*

I didn't realize it was such a sudden switch, you're probably right then.

Onkel Neal
09-16-07, 09:57 AM
I always heard that about tornadoes, not hurricanes. Not sure how valid it is, but if you open doors and windows during a hurricane, the house will fill with rainwater in about 20 seconds :lol:

kurtz
09-16-07, 11:01 AM
I always heard that about tornadoes, not hurricanes. Not sure how valid it is, but if you open doors and windows during a hurricane, the house will fill with rainwater in about 20 seconds :lol:

Perhaps the advice should be open doors and windows and wear your swimming trunks:)

LobsterBoy
09-16-07, 11:26 AM
A tornado is a rapidly rising column of air. The high speed (up to 250-300) coupled with the rising motion is what causes the damage. I haven't seen scientific tests done to prove or disprove the myth of the air pressure change destroying a house, but it is widely accepted as an unnecessary risk to run around opening windows in the face of an impending tornado. Why? If the tornado beats you to the window the broken flying glass is an immediate health hazard.
The advice is to let the insurance take care of the damage. Take shelter and worry about the rest later.

We don't see many hurricanes here in Minnesota, so I don't know as much about them, but the most dangerous winds are in the northeast section of the eye wall. The winds rotate and lift, but at a slower rate (and much larger scale). There is also a tornado risk within the bands of the hurricane. If your house can withstand the high winds of the eye wall, it will probably be fine with the pressure difference in the eye. The lower the pressure of the eye (Katrina was the lowest I've seen at roughly 900mb or 9/10ths normal atmosphere) is what creates the high winds. So, for the pressure to be substantial enough to be a danger to a structure, the high winds associated with it will always bring a greater danger than the central pressure of the eye.

PS I'm not a meteorologist, but I have a sister who is. Never ask a meteorologist, "How about the weather?" to make small talk :damn: :damn: :damn:

Etienne
09-16-07, 11:36 AM
Rule #7 of the Intertube : Alway check snopes :-D

http://www.snopes.com/science/hurricane.asp

Oberon
09-16-07, 11:39 AM
PS I'm not a meteorologist, but I have a sister who is. Never ask a meteorologist, "How about the weather?" to make small talk

I have an uncle who is a meteorologist and I can only echo this advice!! :arrgh!:

Seriously though, while on paper it's a good idea to have open windows to prevent a pressure based explosion of the house, chances are that even if your house doesn't explode it's going to get a few tons of debris dropped on it....and if it's a direct hit then the house is done for anyway.
Thankfully there's not many tornadoes in Suffolk, or hurricanes, but I have done a bit of reading up about both...occording to one book I read which was written in the 1950s (surprisingly good even from the early age of Doppler) there was one recorded incident of a pea being found inside an egg after a tornado...but (get this) the shell of the egg was untouched.

Work that one out... :hmm:

ASWnut101
09-16-07, 01:03 PM
Rule #7 of the Intertube : Alway check snopes :-D

http://www.snopes.com/science/hurricane.asp

The only thing I don't like about that article is the part about plywood coverings on the windows.

Other than that, Neal is right. Don't bother to open your windows during a hurricane unless you've got some damn good flood insurance.

The Munster
09-16-07, 01:13 PM
Rule #7 of the Intertube : Alway check snopes :-D

http://www.snopes.com/science/hurricane.asp

Thanks for the link, very informative :up: