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AMCrenshaw
08-21-2009, 08:28 AM
Would a sandstorm put out a fire, make the fire worse, or not affect the fire?



AMC

GeorgeK
08-21-2009, 08:50 AM
I think it would depend upon the type and size of the fuel source. Wind will provide more oxygen, but a big storm and a small fire, the sand wins. A sandstorm hitting an oil refinery might turn it all into a heaping pile of burning asphalt. I'm just guessing. It's not my field.

Lhun
08-22-2009, 01:35 PM
The wind could provide more oxygen, making the fire burn faster (unless it's small enough to get blown out). On the other hand if the sandstorm piles up sand in the location of the fire, sooner or later it'll suffocate. If there are large, hard pieces of fuel burning, it's imaginable that the abrasion from the sand would remove the burning part on the surface and blow the fire away more than blow it out, but it's impossible to theoretically predict details like that. Only way to find out would be to try, and it might still be a 50/50 affair that happens differently every time.

Ruv Draba
08-23-2009, 01:03 AM
It depends. A fire needs heat, oxygen and fuel. A strong wind can increase the available oxygen, blow away the heat or the fuel. Sand can pile up to smother the oxygen, contaminate the fuel or soak up the heat.

http://www.wingello.rfsa.org.au/FireFacts/fueltri.gif

geardrops
08-23-2009, 04:32 AM
Would a sandstorm put out a fire, make the fire worse, or not affect the fire?

Yes.

BigWords
08-24-2009, 05:40 AM
In SF or fantasy there is nothing to say that the heat couldn't be so immense as to turn the sand into glass, and a wave of sand frozen into glass is a cool visual.

dgiharris
08-27-2009, 12:45 PM
Depends on the density of the sand storm.

So, lets say we are talking about a forest fire. That is about as bad as a natural fire can get. And for the sake of argument, lets say you have a forest smack dab in the middle of the Iraqi desert.

and lets say this bad boy is the sandstorm

http://i.dailymail.co.uk/i/pix/2009/03/10/article-1160962-03D1ACD9000005DC-593_634x423.jpg

Now, there are multiple aspects to fire. The most popular and well known is what is provided by Ruv Draba's cool pic

However, another less popular aspect is the 'type' of heat radiated by fire. The main reason why forest fires are so bad is due to the radiative heat (IR heat) + conventive heat (hot air/fire). THe radiative heat, that is, energy in the electromagnetic spectrum can heat something to over 1100 degrees F which is more than adequate for combustion. The conventive heat is more direct, removes moisture from the air which makes burning easier. It also carries the heat directly to an object to aid in combustion.

Now, enter the sandstorm.

The Sandstorm would completely dissimate the radiative heat. The particles of sand would absorb the heat and refract the IR radiation all over the place to the point of uselessness.

Now we are left with conductive heat. Likewise, the sand would absorb that too.

Now we are left with Rub Draba's basic chart.

It is my belief that a sufficiently dense sandstorm applied over a long period of time (i.e. hours) would contain a forest fire, prevent it from spreading, and thus, stationary, the fire would burn itself out.

If the density of sand was high enough to equate to a few pounds of sand per square foot, then you have enough to smother the fire.

So the answer to your question is yes. If you have a sandstorm, one of those storms where you can't see your hand in front of your face, then yes, over a period of a 3 hours, it would be sufficient to smother a forest fire. Reason I say 3 hours is that is about how long a log will burn by itself.

The last thing I will say is that the Sandstorm must be greater in scope than the forest fire. If the forest fired covered 100 square miles, then the sandstorm would need to be 400 square miles with a steady flux washing over the forest fire. Essentially, the sandstorm is a heat sink, but a heat sink needs to be big enough to drain the source, otherwise, it is not a heat sink.

Mel...

dgiharris
08-27-2009, 12:58 PM
Would a sandstorm put out a fire, make the fire worse, or not affect the fire?


Just thought I'd add another thing here.

It is possible for a sandstorm to make a fire worse. If there is moisture in the air and a 'light' sandstorm came by and swepth through an area (lets say the sandstorm lasted 30 minutes), it would take the moisture out of the air making the fire spread easier.

Mel...

AMCrenshaw
08-28-2009, 08:14 AM
thanks for the help peeps

dgiharris
08-28-2009, 08:42 AM
Just had another thought about this scenario.

THe problem with the sand storm is that it contains no water. Sand is more of an insulator than a conductor, meaning that it will isolate the heat, but won't 'remove' as much of the heat as I indicated above. What this means, is that the heat will be more or less trapped underneath the sand. once the Sand Storm has finished, if there is sufficient wind to blow away the smothering sand, then the fire should have very little trouble kickstarting itself back to life and continuing like it was before.

Now, if the sand storm 'buries' the fire and there is no more wind activity for 8hrs, then the heat will naturally dissipate through the ground and cool off enough to where it shouldn't ignite upon being released.

So the questions are. How bad is the sand storm? How long is the sand storm? What is the weather after the sand storm?

Mel...

Maryn
08-28-2009, 04:51 PM
I've been in a half-dozen sandstorms of the magnitude in that picture, and my gut says that while the airborne particles might smother smoldering grass, there simply isn't enough in suspension to put out raging flames in a vertical structure or a dry forest. No way any of the ones I experienced had more than an ounce or two of airborne solids per square foot, if that.

'My' sandstorms were short-lived, under 90 minutes, with sustained winds around 50-65. The airborne particles included some sand but a great deal more dust. The total amount deposited was under a half-inch, often under a quarter-inch, during a huge, billowing storm that raged more than an hour.

Of course, setting makes a difference. I was in the Sonoran Desert, in a suburb of Phoenix, where the topsoil is not especially sandy. Move such a storm to the Sahara, or to Yuma, and you get different results.

Maryn, just chiming in