[meteorite-list] More exact information about the norwegian fall
test Walter L. Newton 1400 Utah Street #101 Golden, Co 80401 Home 303-279-3046 Cell 303-906-9653 __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
[meteorite-list] More exact information about the norwegian fall
List, I have tried getting more exact information on this fall. In Norway any more exact info has not come out in the last days as far as I know. Partly this is because the first sensational rush has died down, and there is no reason to believe a Hiroshima explosion or anything aproximating that took place. Neither, as I write in another post, is an impact point or crater/scar found. The astromomers/scientist involved is not letting out more information right know. They are probably considering what to do, or maybe considereing just waiting to see if anything more pops up. Personally I have been gathering information about this event using the best info I can find. I will put out some preliminary results, just to get this case in a more sensible direction: I have found an endpoint height using the local witness information and photos (this is all my work): Endpoint (Hemmungspunkt): 27.8 km (quite certain) Inclination (quite uncertain) : near 45 degrees Coming from direction : W through N to E Visible in an area of over 400 km. Sounds (explosions etc.) for about 100 km , possibly more. Sounded like a canon, rifle shot, thunder. As known, many was awaken by the sounds, hypersonic bang/explosion in the North Reisadalen area. Light phenomena: Even though there was a midnight sun low in the north, the meteor lit up the mountains and landscape, it was like a white lightning. The fireball was red in color and was fragmenting. Only two persons has come out in the media with photos. There seems to be no video. A bit unfortunately these two persons are placed just a few km from each other and around 60 to 80 km from the explosion. So I wonder what the list make out of these more precise facts? One question I have: How much further from the retardation point (end point) in km would the pieces travel given the numbers above? Bjørn Sørheim, in Norway __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] More exact information about the norwegian fall
Hello Chris, I just checked some weather charts from that day and time. It seems at ground level there would be not much more than 5 m/s from southwest blowing at the outskirts of a Low near Jan Mayen in the Northermost Atlantic. With winds aloft I have no experience. Any easy way to come up with a wind profile for that location and time, that is up to 30 k m? I see on the best meteor photos of this event, that there is a thin line going completly straight out forward of the big event. Meaning those particles that survived continued without retardation. (There seems also to be a small event forward of the big one.) Wouldn't that mean in this and in the general case that some travel (forward (would like to know the average) is the norm? Bjørn Sørheim At 20:51 14.06.2006, you wrote: Hi Bjorn- A strewn field need not be forward of the retardation point at all. You need to look at the wind conditions, since that is very important in determining the fall zone. In the absence of other information, the best place to start searching is directly under the retardation point (or under any disruption events). Reports of sound are very useful- when you have found an area with many witnesses to sound, there's a good chance you are also near any possible fall zone. Chris * Chris L Peterson Cloudbait Observatory http://www.cloudbait.com - Original Message - From: Bjorn Sorheim [EMAIL PROTECTED] To: meteorite-list@meteoritecentral.com Sent: Wednesday, June 14, 2006 8:29 AM Subject: [meteorite-list] More exact information about the norwegian fall List, I have tried getting more exact information on this fall. In Norway any more exact info has not come out in the last days as far as I know. Partly this is because the first sensational rush has died down, and there is no reason to believe a Hiroshima explosion or anything aproximating that took place. Neither, as I write in another post, is an impact point or crater/scar found. The astromomers/scientist involved is not letting out more information right know. They are probably considering what to do, or maybe considereing just waiting to see if anything more pops up. Personally I have been gathering information about this event using the best info I can find. I will put out some preliminary results, just to get this case in a more sensible direction: I have found an endpoint height using the local witness information and photos (this is all my work): Endpoint (Hemmungspunkt): 27.8 km (quite certain) Inclination (quite uncertain) : near 45 degrees Coming from direction : W through N to E Visible in an area of over 400 km. Sounds (explosions etc.) for about 100 km , possibly more. Sounded like a canon, rifle shot, thunder. As known, many was awaken by the sounds, hypersonic bang/explosion in the North Reisadalen area. Light phenomena: Even though there was a midnight sun low in the north, the meteor lit up the mountains and landscape, it was like a white lightning. The fireball was red in color and was fragmenting. Only two persons has come out in the media with photos. There seems to be no video. A bit unfortunately these two persons are placed just a few km from each other and around 60 to 80 km from the explosion. So I wonder what the list make out of these more precise facts? One question I have: How much further from the retardation point (end point) in km would the pieces travel given the numbers above? Bjørn Sørheim, in Norway __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] More exact information about the norwegian fall
Hi Bjørn- The important wind data is for higher altitudes. I don't have a good source for this information in Norway- maybe the weather service? For the American events I investigate I use radiosonde data produced or collected by NOAA. This provides wind speed and direction up to 30km height twice daily. It is usually possible using one or two datasets to get a good estimate of winds even in remote locations far from active monitoring. I've only seen one image of the fireball- are there more? That one appeared to show only luminous trail- nothing like you describe. There doesn't seem to be a terminal explosion, but rather a large disruption in the middle (which IMO reduces the likelihood of meteorites). Unless the object makes it to the ground carrying cosmic velocity, there is always a retardation point and it isn't possible for any material to continue much beyond this with much speed. The atmospheric drag forces are simply too large. The point of retardation is usually where the drag forces are greatest, and material is decelerating very rapidly- sometimes the forces are greater than the material strength of the parent body. Forward motion is rapidly lost and the fall becomes vertical, typically through zones of high wind speed (30-50 kts or more). So while the fractured material may move one or two kilometers forward of the retardation point, the winds are sufficient to move it ten kilometers or more during dark flight. Of course, the higher the point of retardation, the more effect the wind will have on the position of a strewn field. So you really do need to have a good handle on the high altitude winds when investigating these things, especially if you are searching in a sparsely inhabited mountainous area. Chris * Chris L Peterson Cloudbait Observatory http://www.cloudbait.com - Original Message - From: Bjorn Sorheim [EMAIL PROTECTED] To: Chris Peterson [EMAIL PROTECTED]; meteorite-list@meteoritecentral.com Sent: Wednesday, June 14, 2006 3:27 PM Subject: Re: [meteorite-list] More exact information about the norwegian fall Hello Chris, I just checked some weather charts from that day and time. It seems at ground level there would be not much more than 5 m/s from southwest blowing at the outskirts of a Low near Jan Mayen in the Northermost Atlantic. With winds aloft I have no experience. Any easy way to come up with a wind profile for that location and time, that is up to 30 k m? I see on the best meteor photos of this event, that there is a thin line going completly straight out forward of the big event. Meaning those particles that survived continued without retardation. (There seems also to be a small event forward of the big one.) Wouldn't that mean in this and in the general case that some travel (forward (would like to know the average) is the norm? Bjørn Sørheim __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] More exact information about the norwegian fall
- Original Message - From: Chris Peterson [EMAIL PROTECTED] To: meteorite-list@meteoritecentral.com Sent: Wednesday, June 14, 2006 5:26 PM Subject: Re: [meteorite-list] More exact information about the norwegian fall Hi Bjørn- The important wind data is for higher altitudes. I don't have a good source for this information in Norway- maybe the weather service? For the American events I investigate I use radiosonde data produced or collected by NOAA. This provides wind speed and direction up to 30km height twice daily. It is usually possible using one or two datasets to get a good estimate of winds even in remote locations far from active monitoring. I've only seen one image of the fireball- are there more? That one appeared to show only luminous trail- nothing like you describe. There doesn't seem to be a terminal explosion, but rather a large disruption in the middle (which IMO reduces the likelihood of meteorites). Unless the object makes it to the ground carrying cosmic velocity, there is always a retardation point and it isn't possible for any material to continue much beyond this with much speed. The atmospheric drag forces are simply too large. The point of retardation is usually where the drag forces are greatest, and material is decelerating very rapidly- sometimes the forces are greater than the material strength of the parent body. Forward motion is rapidly lost and the fall becomes vertical, typically through zones of high wind speed (30-50 kts or more). So while the fractured material may move one or two kilometers forward of the retardation point, the winds are sufficient to move it ten kilometers or more during dark flight. Of course, the higher the point of retardation, the more effect the wind will have on the position of a strewn field. So you really do need to have a good handle on the high altitude winds when investigating these things, especially if you are searching in a sparsely inhabited mountainous area. Chris * Chris L Peterson Cloudbait Observatory http://www.cloudbait.com - Original Message - From: Bjorn Sorheim [EMAIL PROTECTED] To: Chris Peterson [EMAIL PROTECTED]; meteorite-list@meteoritecentral.com Sent: Wednesday, June 14, 2006 3:27 PM Subject: Re: [meteorite-list] More exact information about the norwegian fall Hello Chris, I just checked some weather charts from that day and time. It seems at ground level there would be not much more than 5 m/s from southwest blowing at the outskirts of a Low near Jan Mayen in the Northermost Atlantic. With winds aloft I have no experience. Any easy way to come up with a wind profile for that location and time, that is up to 30 k m? I see on the best meteor photos of this event, that there is a thin line going completly straight out forward of the big event. Meaning those particles that survived continued without retardation. (There seems also to be a small event forward of the big one.) Wouldn't that mean in this and in the general case that some travel (forward (would like to know the average) is the norm? Bjørn Sørheim __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] More exact information about the norwegian fall
Hi, List, As will have been noticed by anybody crazy enough to follow all stuff, I have been using the on-line Impact Calculator at LPL based on the most complete model of Jay Meosh to try and approximate what size, speed, and. kind of object would match the description of the Great Norway Rock http://www.lpl.arizona.edu/impacteffects/ By now, as reports change and more details come in, I've run that calculator many hundreds of times trying to create a match for the descriptions. After that many times, I began to get suspicious when I began to get some inconsistent results, such as big changes in its results with only small changes in input parameters, so I started testing the model. I very quickly detected some very odd behavior on its part. Taking a specific run of the model which had produced a good blast (airburst) with seismic effects and plenty of noise, I altered one parameter by the smallest unit amount: I changed the angle of entry from 45 degrees to 44 degrees. Obviously, such a small change should only produce a very slight change IN THE REAL WORLD, but in the model -- all the blast, seismicity, and sound vanished from the results! I was able to get this bad behavior to repeat in other examples, and with other parameters. Some runs hold up better than others, but basically what happens when you get more bad than good answers, you lose all trust in ANY result from the model. You look at every change you induce and say is this right or too much? Too little? How accurate? And then, you give up on the model. So, consider this a caution for anyone else thinking of relying what seemed to be a very convenient and useful tool for impact scenarios. Treat its results as a guide only, at best. While I was fiddling with these incoming fireball simulations, Chris Petersen sent me some emails off-line, trying to gently convince me that a spectacular fireball did not have to be a spectacularly big object and the reported Norwegian fall did not need to be anything like as big as I supposed. He cited some very convincing real-world examples: Well, there are models and there are models (and there is reality). That model may have many useful elements, but consider one actual example. I have a very well characterized event over southwest Colorado from 2002. The meteoroid fragmented at a height of 36 km and dissipated 1e10 joules, or about 2.4 tons TNT. The estimated entry mass was 95 kg. This event was recorded barometrically at three stations, the farthest being 720 km away. Witnesses reported sounds up to 64 km from the terminal explosion. The fireball lit up entire valleys bright enough to stimulate full color vision (the absolute visual magnitude was -17). The explosion produced a signal on a seismometer 325 km away. This event may have produced up to 2 kg of meteorites, but nothing has been recovered. One item that bears repeating is: There are models and there are models (and there is reality). Sadly true. I should have known better. It's clear from the example that the Norwegian observations could be produced by an object much less grandiose than what I suggested. The Melosh model's 34 ton intruder could end up to be a 34 pound rock! Well, maybe a 340 pound rock... In all fairness, I should mention that this on-line calculator gives users one disclaimer about its performance, These results come with ABSOLUTELY NO WARRANTY, so it's not like we weren't warned... a little. I can second that. Use with Caution. Sterling K. Webb - __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
