roy@phri.UUCP (Roy Smith) (05/28/89)
[sci.physics isn't really right, but there isn't a sci.geo, or at least
not yet, so I figured sci.physics isn't too bad a place for this]
This morning, I was sitting at home connected via my TrailBlazer
Plus. It was raining a bit. Suddenly I heard a soft <click>, like a
relay. It sounded exactly like a modem hanging up the line. Before I even
finished recognizing the noise, there was an amazingly bright lightning
flash (it must have been *very* close) almost immediately followed by about
the loudest *BOOM* of thunder I've ever heard, with ba-roo-oom-omm
grumblings lasting for a few seconds. It set off a half dozen car alarms
on the block.
It also zapped the ram in my 'blazer. This is the newer style one
in the white plastic case. Not only did it make it hang up the line, but
it cleared all the numbers stored in ram (ATN? showed all the stored
numbers to be blank). It didn't bother the eeprom, just the ram. The
blazer didn't crash completely; it still responded to commands and neither
the terminal I was using (a CIT-101e) nor a Mac Plus sitting 8 feet away
were bothered.
My physics question about all this is, what was the click I heard?
I thought it was just the phone line relay, but my wife, in the next room,
claims to have heard it too (the relay is *far* too soft for that). Does
up-close lightning make a >click< just before the *BA-ROOOM*?
--
Roy Smith, System Administrator
Public Health Research Institute
{allegra,philabs,cmcl2,rutgers,hombre}!phri!roy -or- roy@phri.nyu.edu
"The connector is the network"henry@utzoo.uucp (Henry Spencer) (05/28/89)
In article <3784@phri.UUCP> roy@phri.UUCP (Roy Smith) writes: > My physics question about all this is, what was the click I heard? >I thought it was just the phone line relay, but my wife, in the next room, >claims to have heard it too (the relay is *far* too soft for that). Does >up-close lightning make a >click< just before the *BA-ROOOM*? Lightning by itself, probably not. Lightning close by electronic equipment, perhaps. What happens when you put a very quick transient voltage through a speaker (like the one in the Trailblazer)? A click. Your wife may have heard the same click you did, or a simultaneous one from something else with a speaker (radio? TV?) that was live at the time. The electromagnetic pulse that caused the transient naturally arrived at the speed of light, thus reaching you slightly before the noise from the bolt itself. -- Van Allen, adj: pertaining to | Henry Spencer at U of Toronto Zoology deadly hazards to spaceflight. | uunet!attcan!utzoo!henry henry@zoo.toronto.edu
piner@pur-phy (Richard Piner) (05/28/89)
In article <3784@phri.UUCP> roy@phri.UUCP (Roy Smith) writes: > > My physics question about all this is, what was the click I heard? >I thought it was just the phone line relay, but my wife, in the next room, >claims to have heard it too (the relay is *far* too soft for that). Does >up-close lightning make a >click< just before the *BA-ROOOM*? >-- I've been lucky (???) enough to see/hear lightning real close. I just happened to be looking out the window when a bolt hit within ten feet or so. At that range lightning bolts have a diameter and they look transparent. I could see through it. Anyway, to answer your question, I think what you heard is the sound of the discharge. Electric sparks make a "snap" sound. This is true of lightning. Most people who have heard that sound from a lightning bolt don't live to tell the tale. Richard Piner
ron@ron.rutgers.edu (Ron Natalie) (05/30/89)
The effect I had with close up lightning occured when I was stopped at a traffic light with the window open. What I heard was a loud hiss, long enough for me to turn around to say what is that and see the lightning strike a lamp post next to the car.
brianm@sco.COM (Brian Moffet) (05/31/89)
In article <2289@pur-phy> piner@newton.physics.purdue.edu.UUCP (Richard Piner) writes: >In article <3784@phri.UUCP> roy@phri.UUCP (Roy Smith) writes: >> >> My physics question about all this is, what was the click I heard? >>I thought it was just the phone line relay, but my wife, in the next room, >>claims to have heard it too (the relay is *far* too soft for that). Does >>up-close lightning make a >click< just before the *BA-ROOOM*? >>-- > > I've been lucky (???) enough to see/hear lightning real close. What I am curious about is why the click *before* he saw the strike (flash of light)? Mr. Smith, is the correct order which you heard/saw things <click> <flash> <Boom> Also about seeing lightning real close, If you could see through it, wouldn't a photograph also show an image through the lightning? Or is lighting being transparent just an optical illusion? brian moffet -- Brian Moffet {uunet,decvax!microsoft,ucscc}!sco!brianm -or- ...sco!alar!brian "I was everything you wanted me to be. You were afraid, I was frightening." My fish and company have policies. I have opinions.
hollombe@ttidca.TTI.COM (The Polymath) (05/31/89)
In article <3784@phri.UUCP> roy@phri.UUCP (Roy Smith) writes: } This morning, I was sitting at home connected via my TrailBlazer }Plus. It was raining a bit. Suddenly I heard a soft <click>, like a }relay. It sounded exactly like a modem hanging up the line. Before I even }finished recognizing the noise, there was an amazingly bright lightning }flash (it must have been *very* close) ... } My physics question about all this is, what was the click I heard? It might have been the pilot bolt before the main bolt. The pilot bolt is a relatively small charge that ionizes the air between the ground and the cloud. This creates an easy path for the main bolt which is, therefore, much more powerful. The pilot bolt would have registered as a click on your speaker. The speaker noise created by the main bolt would have been drowned in the distraction of the flash and thunder. -- The Polymath (aka: Jerry Hollombe, hollombe@ttidca.tti.com) Illegitimati Nil Citicorp(+)TTI Carborundum 3100 Ocean Park Blvd. (213) 452-9191, x2483 Santa Monica, CA 90405 {csun|philabs|psivax}!ttidca!hollombe
mhw@wittsend.LBP.HARRIS.COM (Michael H. Warfield (Mike)) (05/31/89)
In article <3784@phri.UUCP> roy@phri.UUCP (Roy Smith) writes: > My physics question about all this is, what was the click I heard? >I thought it was just the phone line relay, but my wife, in the next room, >claims to have heard it too (the relay is *far* too soft for that). Does >up-close lightning make a >click< just before the *BA-ROOOM*? Just as a fast guess it was probably inductive pick-up directly into the Trailblazer speaker (if that's where you heard it from) or possibly from d*mn near anything capable of picking up a magnetic field and generating mechanical motion. Several years ago I was a broadcast supervisor at a Mid-West NBC-TV affiliate. One evening we where having a "dry-lightening" storm in the area. Lightening strikes were occuring in the 5 to 10 mile range by timing the thunder (you know count the seconds and divide by 6). I was outside the transmitter building during a short power outage. Every time a lightening flashed inside a 10 mile radius, the guy wires on our 1,000 foot tower would "hiss" and "click". Since the tower was VERY well grounded and the lightening was a fair distance away (none less than five miles or I wouldn't have been OUTSIDE!), I discounted the possiblity of local static discharge and figured it to be some sort of inductive or electromagnetic effect. If the lightening was as close as you say, you're probably lucky the click wasn't from thermal expansion as your modem melted its case :-). I have seen lightening and its effects, up close, TOO OFTEN, and I know one thing for sure. You cannot predict just what it is going to do or what peripheral effects it can have! The magnetic fields around that tremendous current pulse alone are staggering! Michael H. Warfield (The Mad Wizard) | gatech.edu!galbp!wittsend!mhw (404) 270-2123 / 270-2098 | mhw@wittsend.LBP.HARRIS.COM An optimist believes we live in the best of all possible worlds. A pessimist is sure of it!
toms@ncifcrf.gov (Tom Schneider) (06/01/89)
In article <7994@galbp.LBP.HARRIS.COM> mhw@wittsend.UUCP (Michael H. Warfield) writes: >storm in the area. Lightening strikes were occuring in the 5 to 10 mile >range by timing the thunder (you know count the seconds and divide by 6). At sea level the speed of sound in air is 1116.45 ft/sec. Dividing by 5280 ft/mile gives the conversion factor (1/4.73) mi/sec. So a better rule is to divide the seconds by 5 to get the distance in miles. Tom Schneider National Cancer Institute Laboratory of Mathematical Biology Frederick, Maryland 21701-1013 toms@ncifcrf.gov
roy@phri.UUCP (Roy Smith) (06/01/89)
In article <2790@scolex.sco.COM> brianm@sco.COM (Brian Moffet) writes:
-> What I am curious about is why the click *before* he saw the strike (flash
-> of light)? Mr. Smith, is the correct order which you heard/saw things
-> <click> <flash> <Boom>
Yup, that was it, with probably a fraction of a second from the
initial click to the start of the BOOM.
--
Roy Smith, Public Health Research Institute
455 First Avenue, New York, NY 10016
{allegra,philabs,cmcl2,rutgers,hombre}!phri!roy -or- roy@alanine.phri.nyu.edu
"The connector is the network"childers@avsd.UUCP (Richard Childers) (06/03/89)
brianm@sco.COM (Brian Moffet) writes: >What I am curious about is why the click *before* he saw the strike >(flash of light)? Mr. Smith, is the correct order which you heard/saw >things ><click> ><flash> ><Boom> My guess would be that the <click> came from the electromagnetic wave that accompanied the lightening strike, electromagnetic radiation. The <flash> _was_ the lightening strike, or the visible radiation. The <boom> was the atmospheric wave that occurred as a result of plasma expanding the air in an erratic path upwards. >Also about seeing lightning real close, If you could see through it, >wouldn't a photograph also show an image through the lightning? Probably not, in that a photographic plate would react strongly to the billions of visible photons that impacted upon it in that millisecond, making it intensely black on the negative and intensively white on the print. >Or is lighting being transparent just an optical illusion? I'd think it's not really transparent. From what I understand, lightening is best understood as a huge spark following the path of least electrical resistance from cathode ( the ground, I believe ) to anode ( the clouds ). This path is rarely a straight one, it is quite turbulent ... and it's not too surprising that a massive pulse of electrons generating heat and light would add substantially to the turbulence. I've heard it represented as a very short-lived channel of plasma. Certainly, it's transparent at some frequency. Maybe gamma rays ... The above information was acquired from a book I read on the topic, I think it's called _Lightening_, by Leon Salanave, published about a decade ago by University of Arizona Press and the culmination of some thirty years of study of lightening in Arizona, at and around Kitt Peak Nat'l Observatory. ( Also my stepfather ... ) >Brian Moffet {uunet,decvax!microsoft,ucscc}!sco!brianm -- richard -- * "We must hang together, gentlemen ... else, we shall most assuredly * * hang separately." Benjamin Franklin, 1776 * * * * ..{amdahl|decwrl|octopus|pyramid|ucbvax}!avsd.UUCP!childers@tycho *
bverreau@mipos2.UUCP (stargazer) (06/05/89)
In article <921@fcs280s.ncifcrf.gov> toms@ncifcrf.gov (Tom Schneider) writes: > At sea level the speed of sound in air is 1116.45 ft/sec. > Dividing by 5280 ft/mile gives the conversion factor (1/4.73) mi/sec. > So a better rule is to divide the seconds by 5 to get the distance in miles. But during a lightning storm the barometric pressure is typically lower than average. How would this affect the speed of sound and the conversion rule? ` Bernie Verreau Microprocessor Design, Intel Corp., Santa Clara, Ca. ' ' ` ` uucp: ..{hplabs|amdcad|qantel|pur-ee|scgvaxd|oliveb}!intelca!mipos2!bverreau ' ' csnet/arpanet: bverreau@mipos2.intel.com `
mcripps@mtuxo.att.com (XMP12-M.CRIPPS) (06/06/89)
> Electric sparks make a "snap" sound. This is true of lightning. > Most people who have heard that sound from a lightning bolt don't > live to tell the tale. While I'm by no means an expert, I lived in a mountainous region of PA for a couple of years, and experienced several nasty storms "up close". On several occasions when I was right in the midst of the storm (i.e., the lightning and thunder were simultaneous), I heard a loud and distinct *click* before the flash. Since I was outdoors at the time, I don't think it was electronic equipment. I also seem to recall reading about this phenomenon (Radio Electronics, several years ago). I thought it was caused by the breakdown before the spark, but, again, I'm not an expert. Mike Cripps mtuxo!mcripps
werme@Alliant.COM (Ric Werme) (06/08/89)
In article <204@mipos3.intel.com> bverreau@mipos2.UUCP (stargazer) writes: >In article <921@fcs280s.ncifcrf.gov> toms@ncifcrf.gov (Tom Schneider) writes: >> So a better rule is to divide the seconds by 5 to get the distance in miles. Agreed - that's even what my father taught me. >But during a lightning storm the barometric pressure is typically lower than >average. How would this affect the speed of sound and the conversion rule? My CRC book doesn't have a decent pressure vs. altitude scale, but is does have a graph of speed of sound vs. altitude. Up to 10 km or so, it varies linearly from 340 M/sec at ground level to 300 m/sec at 10 km. The face of my altimeter (better than a compass for hiking on mountain trails) shows pressure falling about 1" of Hg per 1000 ft. Sorry about mixing units wildly, but I didn't design them! Pressure drops in front of thunderstorms are only fraction of an inch; lightning 10km. up is far enough away to be boring unless you're flying a pressurized plane. Stick to the 5 seconds. -- | A pride of lions | Eric J Werme | | A gaggle of geese | uucp: decvax!linus!alliant | | An odd lot of programmers | Phone: 603-673-3993 |
richard@aiai.ed.ac.uk (Richard Tobin) (06/14/89)
In article <17938@mimsy.UUCP> chris@mimsy.UUCP (Chris Torek) writes: > My guess is that this is for sea level (760 torr); it does not say. "torr"? Is that an abbreviation for Toreks? -- Richard -- Richard Tobin, JANET: R.Tobin@uk.ac.ed AI Applications Institute, ARPA: R.Tobin%uk.ac.ed@nsfnet-relay.ac.uk Edinburgh University. UUCP: ...!ukc!ed.ac.uk!R.Tobin
lars@iclswe.UUCP (Lars Tunkrans) (06/16/89)
In article mcripps@mtuxo.att.com (XMP12-M.CRIPPS) writes: >> Electric sparks make a "snap" sound. This is true of lightning. >> Most people who have heard that sound from a lightning bolt don't >> live to tell the tale. 5 years ago I was 50 to 100 feets from a lightning bolt and I did indeed hear the " CLICK ". It was pretty distinctive too. -- // ///// /// | Lars Tunkrans Distributed Resource Systems support. // /// /// | UUCP: {uunet,mcvax,munnari,cernvax,diku,inria,prlb2,tut /// /// /// | ,ukc,unido} !sunic!iclswe!lars Phone +46 (0)76096368 /// ///// /////// | ( Standard Disclaimer )
smryan@garth.UUCP (s m ryan) (06/20/89)
>"torr"? Is that an abbreviation for Toreks?
Torricelli.
--
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for maiden's sake her brothers fight, Why does the porridge bird
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