New Mexico Fire-Devils

[Larry Pardue]

Greetings:

Last week, around Wednesday, there was a large grass fire west of Portales,
New Mexico, USA. The wind was around 45 knots and it was warm.

Albuquerque television station KOB aired some video tape of the fire that I
found astounding. They showed two, what I would call, fire-devils. The
fire-devils were moving at near the speed of the wind and were rotating
rapidly and in fact looked just like dust-devils made of fire. I did not
record the early footage but was able to get some later that did not show as
much of the incident.

In my first capture

http://n5lp.net/Floyd1.JPG

the first fire-devil has just hit the highway, where it stalled a bit. This
one was shorter and broader than the following one.

http://n5lp.net/Floyd2.JPG

Both of them crossed the highway. It looked like it would have been pretty
interesting from the viewpoint of one of the cars.

These two picture frames are on the order of one second apart in real time.

I have never heard of this phenomenon before. Is there another term for it?

Larry Pardue 2I

[Jack Daniels]

Hmmmmmmmmmmm

Nice thermals



"Larry Pardue" > wrote in message
...
> Greetings:
>
> Last week, around Wednesday, there was a large grass fire west of
> Portales, New Mexico, USA. The wind was around 45 knots and it was warm.
>
> Albuquerque television station KOB aired some video tape of the fire that
> I found astounding. They showed two, what I would call, fire-devils. The
> fire-devils were moving at near the speed of the wind and were rotating
> rapidly and in fact looked just like dust-devils made of fire. I did not
> record the early footage but was able to get some later that did not show
> as much of the incident.
>
> In my first capture
>
> http://n5lp.net/Floyd1.JPG
>
> the first fire-devil has just hit the highway, where it stalled a bit.
> This one was shorter and broader than the following one.
>
> http://n5lp.net/Floyd2.JPG
>
> Both of them crossed the highway. It looked like it would have been
> pretty interesting from the viewpoint of one of the cars.
>
> These two picture frames are on the order of one second apart in real
> time.
>
> I have never heard of this phenomenon before. Is there another term for
> it?
>
> Larry Pardue 2I
>

[Marc Ramsey]

Jack Daniels wrote:
> Hmmmmmmmmmmm
>
> Nice thermals
>

Look at this, an artificial thermal generator:

http://vortexengine.ca/

[Bill Daniels]

"Larry Pardue" > wrote in message
...
> Greetings:
>
> Last week, around Wednesday, there was a large grass fire west of
Portales,
> New Mexico, USA. The wind was around 45 knots and it was warm.
>
> Albuquerque television station KOB aired some video tape of the fire that
I
> found astounding. They showed two, what I would call, fire-devils. The
> fire-devils were moving at near the speed of the wind and were rotating
> rapidly and in fact looked just like dust-devils made of fire. I did not
> record the early footage but was able to get some later that did not show
as
> much of the incident.
>
> In my first capture
>
> http://n5lp.net/Floyd1.JPG
>
> the first fire-devil has just hit the highway, where it stalled a bit.
This
> one was shorter and broader than the following one.
>
> http://n5lp.net/Floyd2.JPG
>
> Both of them crossed the highway. It looked like it would have been
pretty
> interesting from the viewpoint of one of the cars.
>
> These two picture frames are on the order of one second apart in real
time.
>
> I have never heard of this phenomenon before. Is there another term for
it?
>
> Larry Pardue 2I
>
>

They would be familiar to people watching Southern California brush fires.
Incendiary bombing raids in WWII produced fire tornadoes that ripped
buildings apart making them burn even faster. They called them
'Firestorms'.

Hijacking this thread a bit, there is an interesting thread on Dr. Jack's
forum about thermal rotation. A thought is that our flight computers might
be able to detect thermal rotation and then suggest a turn direction to
maximize climb.

Bill Daniels

[W.J. \(Bill\) Dean \(U.K.\).]

If thermals rotate, why don't the clouds rotate?

W.J. (Bill) Dean (U.K.).
Remove "ic" to reply.

>
> "Bill Daniels" > wrote in message
> ...
>
> They would be familiar to people watching Southern California brush fires.
> Incendiary bombing raids in WWII produced fire tornadoes that ripped
> buildings apart making them burn even faster. They called them
> 'Firestorms'.
>
> Hijacking this thread a bit, there is an interesting thread on Dr. Jack's
> forum about thermal rotation. A thought is that our flight computers
> might
> be able to detect thermal rotation and then suggest a turn direction to
> maximize climb.
>
> Bill Daniels
>

[Bob Korves]

Marc Ramsey > wrote in
. net:

> http://vortexengine.ca/

Wanna buy a bridge to go with that Atmospheric Vortex Engine?
-Bob

[BTIZ]

They do.. ever see the underside of a storm just before the tornado shows
itself?

Also, Doppler study of developing thunderstorms show rising rotation within
the cloud as it builds..

I'll have to go find that web page on that...
BT

"W.J. (Bill) Dean (U.K.)." > wrote in message
...
> If thermals rotate, why don't the clouds rotate?
>
> W.J. (Bill) Dean (U.K.).
> Remove "ic" to reply.
>
>>
>> "Bill Daniels" > wrote in message
>> ...
>>
>> They would be familiar to people watching Southern California brush
>> fires.
>> Incendiary bombing raids in WWII produced fire tornadoes that ripped
>> buildings apart making them burn even faster. They called them
>> 'Firestorms'.
>>
>> Hijacking this thread a bit, there is an interesting thread on Dr. Jack's
>> forum about thermal rotation. A thought is that our flight computers
>> might
>> be able to detect thermal rotation and then suggest a turn direction to
>> maximize climb.
>>
>> Bill Daniels
>>
>
>

[Bill Daniels]

"W.J. (Bill) Dean (U.K.)." > wrote in message
...
> If thermals rotate, why don't the clouds rotate?
>

I take it you haven't been to a trailer park in Oklahoma in tornado season.

Bill Daniels

[Eric Greenwell]

W.J. (Bill) Dean (U.K.). wrote:
> If thermals rotate, why don't the clouds rotate?

Apparently, most thermals lose what rotation they have by the time the
cloud forms, or perhaps forming a cloud causes the end of the rotation.
I have seen (albeit rarely) dust devils that went to cloud base at 6000'
to 8000' agl, but did not notice any rotation in the cloud itself. The
diameter of the dust devil was much less than that cloud diameter, so I
would not expect the entire cloud to rotate.

Of course, unless you intend to fly in a cloud (not likely for us in the
USA), it's direction of rotation isn't important.


--
Change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA

[Denis]

Eric Greenwell a écrit :
> W.J. (Bill) Dean (U.K.). wrote:
>> If thermals rotate, why don't the clouds rotate?
>
> Apparently, most thermals lose what rotation they have by the time the
> cloud forms, or perhaps forming a cloud causes the end of the rotation.
> I have seen (albeit rarely) dust devils that went to cloud base at 6000'
> to 8000' agl, but did not notice any rotation in the cloud itself. The
> diameter of the dust devil was much less than that cloud diameter, so I
> would not expect the entire cloud to rotate.

If the rotation is stationary, you cannot see the rotation of the cloud,
just as you cannot see lenticular clouds move... But if there are dust
devils, clouds do rotate !


--
Denis

R. Parce que ça rompt le cours normal de la conversation !!!
Q. Pourquoi ne faut-il pas répondre au-dessus de la question ?

[Martin Gregorie]

Bob Korves wrote:
> Marc Ramsey > wrote in
> . net:
>
>> http://vortexengine.ca/
>
> Wanna buy a bridge to go with that Atmospheric Vortex Engine?
> -Bob

Quite. The Solar Chimney technology (trialled in Spain and, I think,
currently being worked on in Australia)

http://www.globalwarmingsolutions.co.uk/the_solar_chimney.htm

looks likely to be much more efficient.


--
martin@ | Martin Gregorie
gregorie. |
org | Zappa fan & glider pilot

[Francisco De Almeida]

I can think of the following reasons why a visibly rotating dust devil =
can end in an apparently spin-less cloud:

1. The angular momentum carried in a dust devil is partially dissipated =
to the neighbouring air through the normal momentum transfer mechanisms =
that occur in all fluid flows, and very strongly in turbulent flows.

2. A rising thermal collects a large amount of surrounding air, =
especially in its final (or higher) stages. This incorporated air likely =
has statistically random angular momentum, thus diluting the specific =
angular momentum in the whole thermal.

3. The thermal widens and the rotation speed drops by the inverse square =
of the radius.

4. The angular velocity drops by the inverse cube of the radius.

So a ten metre wide dust devil rotating once every two seconds can turn =
into a two hundred wide cloud rotating once every sixty hours, without =
violating any physical laws.

Regards

[Francisco De Almeida]

Oops! Made a mistake in point 4 of previous message.

So, where I wrote "once every sixty hours", please
read "once every six hours".

The cloud will anyway seem devoid of rotation to any human observer.

Regards

[Malcolm Austin]

The idea looks to be interesting, although the problems in producing a
chimney
with a height of 1000 metres would be interesting. :-(

And more importantly, isn't this a bit high for a first thermal off of the
launch? ;-)

Be nice to have a dedicated thermal just off the runway though!

Malcolm...

"Martin Gregorie" > wrote in message
...
> Bob Korves wrote:
>> Marc Ramsey > wrote in
>> . net:
>>
>>> http://vortexengine.ca/
>>
>> Wanna buy a bridge to go with that Atmospheric Vortex Engine?
>> -Bob
>
> Quite. The Solar Chimney technology (trialled in Spain and, I think,
> currently being worked on in Australia)
>
> http://www.globalwarmingsolutions.co.uk/the_solar_chimney.htm
>
> looks likely to be much more efficient.
>
>
> --
> martin@ | Martin Gregorie
> gregorie. |
> org | Zappa fan & glider pilot

[bagmaker]

There are some very optimistic people working on a 1000m high chimney in the prime soaring country north of Mildura, Australia at this very moment.
I asked the question on our aussie site if it could be used as a thermal generator for gliding, everyone was confident it would be no problem BEFORE twin towers 911, not now.
Another good one George, thanks.

[Martin Gregorie]

Francisco De Almeida wrote:
> Oops! Made a mistake in point 4 of previous message.
>
> So, where I wrote "once every sixty hours", please
> read "once every six hours".
>
> The cloud will anyway seem devoid of rotation to any human observer.
>
I certain I've read that, on a calm day, if you lie on your back and
cloud watch, you CAN see them rotate, just very slowly.

Can't remember where I read that, though.


--
martin@ | Martin Gregorie
gregorie. |
org | Zappa fan & glider pilot