A spectacular fire whirl developed at the Sam Fire in Los Angeles County, California, a few days ago, and was caught on camera. Wildfire Today reports:
The KTLA Channel 5 helicopter captured some interesting video of an impressive fire whirl. It’s hard to appreciate it from seeing still photos since it did not appear to be very tall like many large fire whirls, but the indrafts it created are fascinating. At the end of the video below, an Air-Crane helicopter dropped water that at least for a while took most of the energy out of it.
Maybe a helicopter pilot can tell us how ballsy it was, or was not, to fly close enough to drop water on the fire whirl.
Fire whirls, much like dust devils, are not uncommon on a fire when the atmosphere is unstable, and are much smaller than fire tornados ... the average size of a fire whirl is usually 33 to 100 feet, with rotational velocities of 22 to 67 MPH.
But a fire tornado dominates the large scale fire dynamics. They lead to extreme hazard and control problems. In size, they average 100 to 1,000 feet in diameter and have rotational velocities up to 90 MPH.
There's more at the link.
Here's the video.
Looking at the way flames dozens, even scores of yards away were sucked into that thing... scary! If that fire got into a residential neighborhood, how could you possibly stop it consuming the entire area? The average domestic garden hose or fire extinguishers would be utterly useless. I'm not sure even fire engines could cope.
Peter
They are a spectacular sight. That fire appears to be burning most in surface fuels - grass and brush - and I wouldn’t expect the ride in the ‘crane to be too bumpy. Its rapid climb on dropping its load could be partially updraft, or maybe the pilot didn’t bother compensating for losing 7-9 tons of load in a few seconds. That was a relatively high drop, so that may say a bit more about the conditions.
ReplyDeleteAround the 1:10min mark you can see small fires starting in the unburnt fuel and sucking back into the main fire. That results from burning material lifted in the updraft. They can be very dangerous for a crew working on the main fire as they can get trapped between the two if they aren’t very aware of what is going on. Spotfires around you can be one of the first signs that you have a hot fire heading in your direction.
Cheers....
Notes from a firefighter:
ReplyDeleteBig Fire - Big Water
Don't fight wildland fire with a fire extinguisher or a garden hose (see above).
Wildland firefighting is a complex and oftentimes dangerous job. Firefighting in the Wildland/Urban interface just adds more complexity. "if that fire got into a residential neighborhood, how could you possibly stop it from consuming the entire area?" - Hard to say - Way too many variables - water supply, access, wind conditions, safety zones and escape route(s), etc, etc...
Just for the very basics of Wildland Firefighting we have 10 Standard Firefighting Orders and 18 Watch Out Situations - and then you need smart, savvy crews with lots of experience - both in leadership and on the lines.
Pretty cool video!!!
Wonder what the temperature difference is between going into the vortex and exiting.
ReplyDeleteNot gonna volunteer to find out. Hotter than Hades.
ReplyDeletePeter
ReplyDeleteThis is footage from the fire that bit a chunk out of Canberra in ‘03..
Gives an idea how what a bad ember attack on a high-wind day can look like.
Cost the city 4 lives and 500 houses in an afternoon.
https://www.youtube.com/watch?v=IzqC_8D12U0
If you have time, this longer bit of footage shows the progression as everything goes to hell.
https://youtu.be/qPpOXH0ADSg
I wasn’t there on the day - fortunately -
Do they spin clockwise or anti-clockwise in Northern Hemisphere?
ReplyDelete