jcato
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Since the 'Sparkies Rant' thread pretty much spent it's energy (and descended into frivolity), I saw very little reason to post this discussion on 'range fires' there - thus, a new thread...
What a range fire *could* look like...
First, before we get any further into this, understand that the photos you are about to see are NOT an uncontrolled fire -- this is a *controlled* (or 'prescribed') burn on a sod farm - set intentionally (but, again, under controlled conditions and with appropriate 'disaster preparedness' taken to assure the fire is contained within a fire resistant perimeter (plowed firebreaks around the extremities of the property or previously burned over areas serving as a firebreak)).
This 'controlled burn' occurred about 10 years ago (during the winter months) on a nearby sod farm that hosted rocket flying for many years (before this event). This is the only time (in my memory - going back to about 1988) that such a management procedure was initiated on this property (and the site was purchased and established in sod only 2 years prior to that). In the years we flew there, there were several instances of a pad fire started by rocket launches - mostly due to spit igniters - and all were extinguished after burning (at most) a few square feet. There were not, as best I recall, any fires started by 'sparky' motors, but that is almost exclusively because there was tight control over when those motors were allowed to be used (i.e. if there was any doubt at all about flammability conditions, the 'sparkies' were not allowed). Launches at this site typically occurred twice a year - in the spring after the grass 'greened' up (less fire danger) and in the fall after the harvest (of grass seed) was concluded (greater fire danger).
I was very fortunate to be able to witness (and photograph) this event -- as the educational value of actually *seeing* what a large scale burn operation on a sod farm is capable of doing is almost immeasurable. I do not recall knowing beforehand that the burn was to take place - but the smoke plume was visible for several miles away (the first photo I took that day (not included) was taken about 2 miles away from the entrance to the site). I live about 6 miles (straight line distance) away, but don't recall that I saw the plume from my home and decided to go investigate - I just can't remember. It was, again, a very fortuitous event, however - due to the learning value it represented in regards to rocket related 'range management' and fire control.
As to additional background: I am a rural property owner (timberland) that has had prescribed burning operations conducted on it - which I conducted with a good friend who is a Registered Forester. I have, additionally, also helped him with other prescribed burns on other properties he managed. My experience, while not overly extensive, is sufficient to understand and appreciate the nature of fire behavior (coupled with additional study of forestry practices) and the conditions (and limits) of safe use of fire (and, conversely, those conditions that make it unsafe). The one overriding reality of using fire as a management practice is just how fast things can transition from 'manageable' to 'unmanageable' (unless one has seen it, one cannot imagine what a 'shot of oxygen' (i.e. a gust of wind) will do to a moderately developed fire and how fast it will happen). Some of the pictures below will give a little hint of that kind of behavior.
{edit: As a particular example of how a fire will react to that 'shot of oxygen', 2 years ago I was burning off a little triangular 'patch' of woods (1 acre) - lighting off one side of the triangle and letting it burn to the opposite vertex (backing into the wind). One side was lagging, so I trailed a line of fire up that edge (to help that side catch up) and the wind (a slight breeze) shifted just a little to come off my back and onto the just ignited edge (i.e. making it a little bit of a head fire). I watched (from about 30 feet away) some 3 foot flames 'explode' to 40 foot flames (i.e. about as tall as the trees) in about 10 seconds. This energy killed about 3 (mature pine) trees that was in the hottest area. If you've never seen fire behave like this, it's very hard to believe it will happen.}
Prescribed Burn Terminology / Techniques:
========================================
The general technique in prescribed burns is to ignite the burn on the downwind side and allow the fire to 'back' into the wind (considerably slower progress and much lower flame heights) - called a "Back" (or 'backing') fire. If conditions warrant (and after the downwind portion of the fire has burned enough to create a substantial area of 'black'), an upwind ignition can take place - a "Head" fire - but these types of fire can get out of hand incredibly fast. Head fires serve a valid purpose - which is good if your downwind firebreaks are sufficiently large to assure the head fire won't jump over as it approaches the break - 'good' because it's all over so fast. Back fires can take hours to complete. A head fire can be over in minutes. One intermediate technique is a "Flank" (or 'flanking') fire - where the ignition occurs in a line going INTO the wind (from the downwind backing fire line) - usually several parallel lines that will then burn into several 'V's - all shortly burning together and, effectively, advancing the backfire line to the head end of the 'V's much faster than if just allowed to burn unaided as a normal back fire. One important caution is that a flank fire is always lit from the downwind (or 'backing') side -- to light a flank fire out in front of a 'head' fire would be almost suicide -- as all the energy is coming toward you and you have nowhere to go (into 'The Black' (i.e. into already burned areas)). One additional technique is a "Ring" fire, where the boundary is secured and the entire perimeter is ignited over a short time period and the fire is allowed to burn to the center - generally quite safe, with one caveat: as the fire converges, the drafting (influx of air) of the (increasingly intense) ring of fire will increase the intensity some fair amount. In timberland, the fire can get so intense it will kill trees -- and this is one reason it is seldom used (except on cutover land, where the additional intensity can assist in consuming the trash from the timber harvesting operations). What you will see here is somewhat a 'Ring' fire.
While some state laws today provide additional restrictions on night burning, traditionally, most prescribed burns will occur in the afternoon up into the evening hours for one very important reason - the temperature is falling and the humidity is rising (both important to keep a fire controllable). Fires ignited in the morning hours face two very ominous conditions for their controllability - the exact reverse of the above: temperatures are rising and humidity is falling - either of which will intensify fire behavior. When you hear (on the news reports) about the fire 'laying down' at night, this is what they mean - the cooler temps and higher humidity can (sometimes dramatically) calm the fire down - which makes control efforts far more successful.
One additional factor that enters into the decision to "go" on a prescribed burn is wind - one of the most critical items that can (very) dramatically change a prescribed burn into a wildfire very quickly. Accordingly, the vast majority of prescribed burns are scheduled to occur 1-3 days after passage of a cold front (here in the East - but there's no special reason this would be limited to certain areas... because...) The winds after a cold front passage are generally very stable (i.e. constantly come from the same direction - blustery for the first day, but calming down with every 24 hour passage of time). Additionally, the rain from the front will dampen the underlying 'duff' (the partially decomposed organic litter under the top, more visible and fresh growth on the forest floor (which would also apply to turfgrass)) - which will remain damp for several days after frontal passage. Here in the east, cold fronts produce northwesterly winds. Winds from the east (mostly) and south (somewhat) are generally not as stable and discourage burn operations for the most part.
===================
I discuss these particulars because some of my comments I make (below) will use some of these terms and also for the reader to contemplate the significance of this in terms of the distinguishing characteristics of a "Prescribed Burn" (what you will see here) from a "Wildfire" (what will most times happen if a rocket launch event causes a fire) - with these extremely critical facts about the reality of what that 'Rocket Launch Fire' represents:
A (rocket) range fire...
* is NOT planned (and, therefore, places the first responders (you) in a position of having almost NO control over any aspect of the fire);
* is NOT ignited at the correct location (relative to winds and firebreaks);
* does NOT even *have* any firebreaks (once it gets very far from it's ignition point);
* will - almost without exception - turn into a 'Head' fire
...(unless you are lucky enough that a dirt road is 100 feet downwind);
* is not ignited when weather conditions (and stability) is optimum (to keep the behavior within bounds);
* will have a fire perimeter, for every single second it burns, that only get's bigger...
... because, being a head fire, it is running at a pretty good clip
... (and this is exactly the opposite of a 'Ring' fire - for every second, the perimeter is getting smaller).
* All of this means that - once this fire reaches the property perimeter (assuming something like a sod farm or harvested farm field), stopping it from crossing over into the adjoining landowner's property is virtually impossible.
There is only one way that a fire like this can be 'corralled' from becoming a very bad day and that is to be right on top of it the instant it ignites (but the same thing applies if you have a grease fire in your kitchen at home - the key principle is forceful and immediate suppression).
It is also this very fact that catches far too many off guard (whether in your kitchen or on the rocket range) --- they *just can't appreciate* how fast things can get very bad. The pictures included here should work (it is my hope) to broaden the perspective a little.
=====================
As to the particular burn shown here, it occurred in the early evening hours of 21 December 2004. The area represented by the photos is approximately 52 acres (the dimensions of this is approximately 2100 feet (N-S) x 1800 feet (E-W)). The grass tops have been killed by frost (generally first occurrence is November). Winds were light and coming from the south to southwest (a little curious, considering the area of ignition - but an adjoining parcel immediately to the north of the tract shown was also burned over just slightly before this tract and the two flame fronts more or less converged at the northern boundary of the 52 acre tract (this is shown by a red line on the plan and most of the pictures). I have placed notations on the photos. I have also captured the 'data bar' from ACDSee (my photo viewer) that shows several pertinent items of each image - most particularly, the time-of-day (including seconds) the picture was taken, which I also notate immediately above (in larger type - for easier viewing - in minutes:seconds (after the hour - 6pm local)). Some of these photos are merged panoramas and some are not -- in order to help the viewer keep things clear, I picked two unique features in the foreground to highlight - an unburned 'frond' of some broom-sedge (box 'A') and a section of a line of weeds along a shallow swale (ditch) (box 'B') that I have notated in every photo where they appear. I recommend that you set your photo viewer to zoom to "actual size" or "100%", so as to give you a correct view on each photo at equal scales - one to the other (some panoramas are horizontal and one is vertical - to give an idea of the height of the smoke column). Some additional comments are with each photo...
The first photo shows the overall site with a scale reference, the area of the burn, the (approx) wind direction and my viewpoint:
In these following photos, the immediate foreground has already been burned over by previous operations - out to the stream edge (see plan view) and up to the road edge running down the centerline of the site (that I'm standing on).
{edit: I've reversed the order of caption/picture to place the caption UNDER the referenced photo}
DSCN3218 - 08m:22s {distance to treeline: left:2200ft | right:2400ft}
This photo (looking SE) is after the far edge (along the treeline) has been ignited (with a 'Gator' type utility vehicle - stringing a line of fire from a 'drip torch') from the left to the right. You can tell the (light) winds are coming from the right (southerly) - and the ignition vehicle is making the turn at the extreme southern end of the tract (on the right edge).
========================
DSCN320 - 10m:30s
Now the right (southerly) edge is beginning to get going and the wind direction is clearer. I have studied the photo and can't definitively identify if the ignition vehicle has turned back to the far perimeter (towards the left - above 'A') - following a minor drainage swale ("M.D.S." on plan view). However, a later picture (14m:42s) shows the vehicle proceding down the near edge (along the major creek ('CREEK' on plan view)) which would be more logical (and less dangerous than having to turn around and backtrack (INto the flame edge) to get back to the near side creek edge). There *does* appear to be some wisps of smoke nearer than the treeline in the background (above and to the left of box 'B') - but the risky nature of doing this coupled with the questionable benefit causes doubt that that would be the case.
========================
DSCN3221 - 12m:42s
This is only 2 minutes and 12 seconds from the previous photo and (I think) conveys the true nature of how fast things can develop (possibly even more than the photos to come). If the ignition vehicle noted previously DID run a second line of fire down the minor drainage swale ("M.D.S." - as described), almost none of that would contribute to the fire extent shown here, as it would be a flanking fire (see discussion above) and any 'excitement' of that line of fire due to wind would be downwind (toward the left edge and away from the increased fire development) - and, as is obvious, the greater extent of development is above and to the right of box 'B'. None of that fire would move back UPwind (to this position) and especially not in 132 seconds - so there's reasonable confidence the development between this photo and 10m:30s (on the areas above and to the right of box 'B') is exclusively due to the shot of oxygen due to the wind:
========================
DSCN3223 - 14m:42s {distance to treeline: left:2100ft | right:2400ft}
Two more minutes have transpired and now the fire has got a good head of 'steam' and is moving rapidly through the tract. You can see the ignition vehicle in the foreground (along the stream edge near box 'A') and the flames from his ignition back towards box 'B' - again, this is a 'flank' fire and it will be trying to 'catch' the ignition vehicle. The separate burn on the left (the north edge of the site) has already about burned over (and, thus, forms the downwind firebreak to be used to 'catch' the (moderate) 'head' fire converging on it. (This part of the fire is a separate burn and is to be ignored).
========================
DSCN3229 - 17m:54s
Three more minutes. The flame front has pretty much arrived at the northern boundary (the red line), as it is very difficult to determine any 'flame edge' anywhere within the burn perimeter.
========================
DSCN3230 - 18m:20s
This photo (a 'stacked' or vertical pan) is taken only 26 seconds after the previous one and is included to give an idea of the magnitude of the vertical extent of the smoke plume. Not any dramatic change within the burn area - about the same as the previous photo:
========================
DSCN3236 - 22m:46s {distance to treeline: left:2100ft | right:2400ft}
About 4 1/2 minutes later, a wide pan of the entire 52 acre tract and the fire is pretty much over - with extensive areas of smoldering grass (it's still a little 'hot' on the northern edge above box 'A'). 14 minutes:24 seconds from very first ignition - a little over 12 minutes from when the fire got going (10:30 photo).
========================
DSCN3246 - 36m:20s
A wider pan - and everything is pretty much over with scattered areas of minor smoldering. 28+minutes from first ignition - 52 acres burned - about 1 acre every 30 seconds.
{edit: It may be more accurate to consider the 'burn' as 'over' at 22m:46s, as the flame front has already transited the entire tract -- 14.4min -- which is about 1 acre every 17 seconds.}
Closing Commentary:
[TRF fussed that the post was too long - so the Closing Commentary will come in a follow-on post]
-- john.
edits: 10-17 - 1:27am - updated site plan, reversed photos/captions, minor edits, additional commentary on fire development
What a range fire *could* look like...
First, before we get any further into this, understand that the photos you are about to see are NOT an uncontrolled fire -- this is a *controlled* (or 'prescribed') burn on a sod farm - set intentionally (but, again, under controlled conditions and with appropriate 'disaster preparedness' taken to assure the fire is contained within a fire resistant perimeter (plowed firebreaks around the extremities of the property or previously burned over areas serving as a firebreak)).
This 'controlled burn' occurred about 10 years ago (during the winter months) on a nearby sod farm that hosted rocket flying for many years (before this event). This is the only time (in my memory - going back to about 1988) that such a management procedure was initiated on this property (and the site was purchased and established in sod only 2 years prior to that). In the years we flew there, there were several instances of a pad fire started by rocket launches - mostly due to spit igniters - and all were extinguished after burning (at most) a few square feet. There were not, as best I recall, any fires started by 'sparky' motors, but that is almost exclusively because there was tight control over when those motors were allowed to be used (i.e. if there was any doubt at all about flammability conditions, the 'sparkies' were not allowed). Launches at this site typically occurred twice a year - in the spring after the grass 'greened' up (less fire danger) and in the fall after the harvest (of grass seed) was concluded (greater fire danger).
I was very fortunate to be able to witness (and photograph) this event -- as the educational value of actually *seeing* what a large scale burn operation on a sod farm is capable of doing is almost immeasurable. I do not recall knowing beforehand that the burn was to take place - but the smoke plume was visible for several miles away (the first photo I took that day (not included) was taken about 2 miles away from the entrance to the site). I live about 6 miles (straight line distance) away, but don't recall that I saw the plume from my home and decided to go investigate - I just can't remember. It was, again, a very fortuitous event, however - due to the learning value it represented in regards to rocket related 'range management' and fire control.
As to additional background: I am a rural property owner (timberland) that has had prescribed burning operations conducted on it - which I conducted with a good friend who is a Registered Forester. I have, additionally, also helped him with other prescribed burns on other properties he managed. My experience, while not overly extensive, is sufficient to understand and appreciate the nature of fire behavior (coupled with additional study of forestry practices) and the conditions (and limits) of safe use of fire (and, conversely, those conditions that make it unsafe). The one overriding reality of using fire as a management practice is just how fast things can transition from 'manageable' to 'unmanageable' (unless one has seen it, one cannot imagine what a 'shot of oxygen' (i.e. a gust of wind) will do to a moderately developed fire and how fast it will happen). Some of the pictures below will give a little hint of that kind of behavior.
{edit: As a particular example of how a fire will react to that 'shot of oxygen', 2 years ago I was burning off a little triangular 'patch' of woods (1 acre) - lighting off one side of the triangle and letting it burn to the opposite vertex (backing into the wind). One side was lagging, so I trailed a line of fire up that edge (to help that side catch up) and the wind (a slight breeze) shifted just a little to come off my back and onto the just ignited edge (i.e. making it a little bit of a head fire). I watched (from about 30 feet away) some 3 foot flames 'explode' to 40 foot flames (i.e. about as tall as the trees) in about 10 seconds. This energy killed about 3 (mature pine) trees that was in the hottest area. If you've never seen fire behave like this, it's very hard to believe it will happen.}
Prescribed Burn Terminology / Techniques:
========================================
The general technique in prescribed burns is to ignite the burn on the downwind side and allow the fire to 'back' into the wind (considerably slower progress and much lower flame heights) - called a "Back" (or 'backing') fire. If conditions warrant (and after the downwind portion of the fire has burned enough to create a substantial area of 'black'), an upwind ignition can take place - a "Head" fire - but these types of fire can get out of hand incredibly fast. Head fires serve a valid purpose - which is good if your downwind firebreaks are sufficiently large to assure the head fire won't jump over as it approaches the break - 'good' because it's all over so fast. Back fires can take hours to complete. A head fire can be over in minutes. One intermediate technique is a "Flank" (or 'flanking') fire - where the ignition occurs in a line going INTO the wind (from the downwind backing fire line) - usually several parallel lines that will then burn into several 'V's - all shortly burning together and, effectively, advancing the backfire line to the head end of the 'V's much faster than if just allowed to burn unaided as a normal back fire. One important caution is that a flank fire is always lit from the downwind (or 'backing') side -- to light a flank fire out in front of a 'head' fire would be almost suicide -- as all the energy is coming toward you and you have nowhere to go (into 'The Black' (i.e. into already burned areas)). One additional technique is a "Ring" fire, where the boundary is secured and the entire perimeter is ignited over a short time period and the fire is allowed to burn to the center - generally quite safe, with one caveat: as the fire converges, the drafting (influx of air) of the (increasingly intense) ring of fire will increase the intensity some fair amount. In timberland, the fire can get so intense it will kill trees -- and this is one reason it is seldom used (except on cutover land, where the additional intensity can assist in consuming the trash from the timber harvesting operations). What you will see here is somewhat a 'Ring' fire.
While some state laws today provide additional restrictions on night burning, traditionally, most prescribed burns will occur in the afternoon up into the evening hours for one very important reason - the temperature is falling and the humidity is rising (both important to keep a fire controllable). Fires ignited in the morning hours face two very ominous conditions for their controllability - the exact reverse of the above: temperatures are rising and humidity is falling - either of which will intensify fire behavior. When you hear (on the news reports) about the fire 'laying down' at night, this is what they mean - the cooler temps and higher humidity can (sometimes dramatically) calm the fire down - which makes control efforts far more successful.
One additional factor that enters into the decision to "go" on a prescribed burn is wind - one of the most critical items that can (very) dramatically change a prescribed burn into a wildfire very quickly. Accordingly, the vast majority of prescribed burns are scheduled to occur 1-3 days after passage of a cold front (here in the East - but there's no special reason this would be limited to certain areas... because...) The winds after a cold front passage are generally very stable (i.e. constantly come from the same direction - blustery for the first day, but calming down with every 24 hour passage of time). Additionally, the rain from the front will dampen the underlying 'duff' (the partially decomposed organic litter under the top, more visible and fresh growth on the forest floor (which would also apply to turfgrass)) - which will remain damp for several days after frontal passage. Here in the east, cold fronts produce northwesterly winds. Winds from the east (mostly) and south (somewhat) are generally not as stable and discourage burn operations for the most part.
===================
I discuss these particulars because some of my comments I make (below) will use some of these terms and also for the reader to contemplate the significance of this in terms of the distinguishing characteristics of a "Prescribed Burn" (what you will see here) from a "Wildfire" (what will most times happen if a rocket launch event causes a fire) - with these extremely critical facts about the reality of what that 'Rocket Launch Fire' represents:
A (rocket) range fire...
* is NOT planned (and, therefore, places the first responders (you) in a position of having almost NO control over any aspect of the fire);
* is NOT ignited at the correct location (relative to winds and firebreaks);
* does NOT even *have* any firebreaks (once it gets very far from it's ignition point);
* will - almost without exception - turn into a 'Head' fire
...(unless you are lucky enough that a dirt road is 100 feet downwind);
* is not ignited when weather conditions (and stability) is optimum (to keep the behavior within bounds);
* will have a fire perimeter, for every single second it burns, that only get's bigger...
... because, being a head fire, it is running at a pretty good clip
... (and this is exactly the opposite of a 'Ring' fire - for every second, the perimeter is getting smaller).
* All of this means that - once this fire reaches the property perimeter (assuming something like a sod farm or harvested farm field), stopping it from crossing over into the adjoining landowner's property is virtually impossible.
There is only one way that a fire like this can be 'corralled' from becoming a very bad day and that is to be right on top of it the instant it ignites (but the same thing applies if you have a grease fire in your kitchen at home - the key principle is forceful and immediate suppression).
It is also this very fact that catches far too many off guard (whether in your kitchen or on the rocket range) --- they *just can't appreciate* how fast things can get very bad. The pictures included here should work (it is my hope) to broaden the perspective a little.
=====================
As to the particular burn shown here, it occurred in the early evening hours of 21 December 2004. The area represented by the photos is approximately 52 acres (the dimensions of this is approximately 2100 feet (N-S) x 1800 feet (E-W)). The grass tops have been killed by frost (generally first occurrence is November). Winds were light and coming from the south to southwest (a little curious, considering the area of ignition - but an adjoining parcel immediately to the north of the tract shown was also burned over just slightly before this tract and the two flame fronts more or less converged at the northern boundary of the 52 acre tract (this is shown by a red line on the plan and most of the pictures). I have placed notations on the photos. I have also captured the 'data bar' from ACDSee (my photo viewer) that shows several pertinent items of each image - most particularly, the time-of-day (including seconds) the picture was taken, which I also notate immediately above (in larger type - for easier viewing - in minutes:seconds (after the hour - 6pm local)). Some of these photos are merged panoramas and some are not -- in order to help the viewer keep things clear, I picked two unique features in the foreground to highlight - an unburned 'frond' of some broom-sedge (box 'A') and a section of a line of weeds along a shallow swale (ditch) (box 'B') that I have notated in every photo where they appear. I recommend that you set your photo viewer to zoom to "actual size" or "100%", so as to give you a correct view on each photo at equal scales - one to the other (some panoramas are horizontal and one is vertical - to give an idea of the height of the smoke column). Some additional comments are with each photo...
The first photo shows the overall site with a scale reference, the area of the burn, the (approx) wind direction and my viewpoint:
In these following photos, the immediate foreground has already been burned over by previous operations - out to the stream edge (see plan view) and up to the road edge running down the centerline of the site (that I'm standing on).
{edit: I've reversed the order of caption/picture to place the caption UNDER the referenced photo}
DSCN3218 - 08m:22s {distance to treeline: left:2200ft | right:2400ft}
This photo (looking SE) is after the far edge (along the treeline) has been ignited (with a 'Gator' type utility vehicle - stringing a line of fire from a 'drip torch') from the left to the right. You can tell the (light) winds are coming from the right (southerly) - and the ignition vehicle is making the turn at the extreme southern end of the tract (on the right edge).
========================
DSCN320 - 10m:30s
Now the right (southerly) edge is beginning to get going and the wind direction is clearer. I have studied the photo and can't definitively identify if the ignition vehicle has turned back to the far perimeter (towards the left - above 'A') - following a minor drainage swale ("M.D.S." on plan view). However, a later picture (14m:42s) shows the vehicle proceding down the near edge (along the major creek ('CREEK' on plan view)) which would be more logical (and less dangerous than having to turn around and backtrack (INto the flame edge) to get back to the near side creek edge). There *does* appear to be some wisps of smoke nearer than the treeline in the background (above and to the left of box 'B') - but the risky nature of doing this coupled with the questionable benefit causes doubt that that would be the case.
========================
DSCN3221 - 12m:42s
This is only 2 minutes and 12 seconds from the previous photo and (I think) conveys the true nature of how fast things can develop (possibly even more than the photos to come). If the ignition vehicle noted previously DID run a second line of fire down the minor drainage swale ("M.D.S." - as described), almost none of that would contribute to the fire extent shown here, as it would be a flanking fire (see discussion above) and any 'excitement' of that line of fire due to wind would be downwind (toward the left edge and away from the increased fire development) - and, as is obvious, the greater extent of development is above and to the right of box 'B'. None of that fire would move back UPwind (to this position) and especially not in 132 seconds - so there's reasonable confidence the development between this photo and 10m:30s (on the areas above and to the right of box 'B') is exclusively due to the shot of oxygen due to the wind:
========================
DSCN3223 - 14m:42s {distance to treeline: left:2100ft | right:2400ft}
Two more minutes have transpired and now the fire has got a good head of 'steam' and is moving rapidly through the tract. You can see the ignition vehicle in the foreground (along the stream edge near box 'A') and the flames from his ignition back towards box 'B' - again, this is a 'flank' fire and it will be trying to 'catch' the ignition vehicle. The separate burn on the left (the north edge of the site) has already about burned over (and, thus, forms the downwind firebreak to be used to 'catch' the (moderate) 'head' fire converging on it. (This part of the fire is a separate burn and is to be ignored).
========================
DSCN3229 - 17m:54s
Three more minutes. The flame front has pretty much arrived at the northern boundary (the red line), as it is very difficult to determine any 'flame edge' anywhere within the burn perimeter.
========================
DSCN3230 - 18m:20s
This photo (a 'stacked' or vertical pan) is taken only 26 seconds after the previous one and is included to give an idea of the magnitude of the vertical extent of the smoke plume. Not any dramatic change within the burn area - about the same as the previous photo:
========================
DSCN3236 - 22m:46s {distance to treeline: left:2100ft | right:2400ft}
About 4 1/2 minutes later, a wide pan of the entire 52 acre tract and the fire is pretty much over - with extensive areas of smoldering grass (it's still a little 'hot' on the northern edge above box 'A'). 14 minutes:24 seconds from very first ignition - a little over 12 minutes from when the fire got going (10:30 photo).
========================
DSCN3246 - 36m:20s
A wider pan - and everything is pretty much over with scattered areas of minor smoldering. 28+minutes from first ignition - 52 acres burned - about 1 acre every 30 seconds.
{edit: It may be more accurate to consider the 'burn' as 'over' at 22m:46s, as the flame front has already transited the entire tract -- 14.4min -- which is about 1 acre every 17 seconds.}
Closing Commentary:
[TRF fussed that the post was too long - so the Closing Commentary will come in a follow-on post]
-- john.
edits: 10-17 - 1:27am - updated site plan, reversed photos/captions, minor edits, additional commentary on fire development
Last edited:
). By the time I got there the wind had already spread the fire larger than what we could put out doing the "boot-scoot boogie", especially when the fire was heading for a tumbleweed choked little ditch-like arroyo. Fire hits that and you don't want to be around, the radiant heat can blister your skin before you can get away. We packed up with one brother going north where there's a huge farm in the middle of the desert. The farmer let my brother call the BLM fire crew then he got on his massive(biggest I've ever seen) Caterpillar road grader, drove down to where the fire was, dropped the rippers and drove around the fire plowing up the desert and cutting a fire brake. 
