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 Foo Off-Topic chit chat with no general subject.

 04-08-08, 06:23 PM #1 East Hill Lanky Lass Thread Starter     Join Date: Sep 2005 Location: Take a deep breath, and ask--What would Sheldon do? Bikes: Nishiki Nut! International, Pro, Olympic 12, Sport mixte, and others too numerous to mention. Posts: 21,462 Mentioned: 0 Post(s) Tagged: 0 Thread(s) Quoted: 1 Post(s) Calculating the size of a rainbow No, I haven't lost my mind (well, not today at least). Mr. East Hill was musing today about how to calculate the apparent size of a rainbow. If this makes sense to anyone, could you please explain how to do this? East Hill __________________ ___________________________________________________ TRY EMPATHY & HAVE LOVE IN YOUR HEART, PERHAPS I'LL SEE YOU ON THE ROAD...
04-08-08, 06:25 PM   #2
jsharr
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It is an algorithm based on the size of the pot of gold.
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 Originally Posted by colorider Phobias are for irrational fears. Fear of junk ripping badgers is perfectly rational. Those things are nasty.

 04-08-08, 06:28 PM #3 Alfster  long time visiter     Join Date: Oct 2005 Location: in the Northern Tundra Bikes: 2005 Trek 6700 disc 2007 Orbea Onix 2009 Raleigh One Way Posts: 615 Mentioned: 0 Post(s) Tagged: 0 Thread(s) Quoted: 6 Post(s) Using the widely accepted, industry standard stride length of a Leprechaun = 1.3 feet, count the number of steps he takes and multiply it by the stride length. This should give you the final distance. Note: if he's carrying his pot of gold make sure you reduce his stride length by a factor of 0.85.
04-08-08, 06:30 PM   #4
jsharr
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Alfster, you are describing ground length of rainbow, but arch is dictated soley by pot of gold size. Once you know length and arch, then you are golden.
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 Originally Posted by colorider Phobias are for irrational fears. Fear of junk ripping badgers is perfectly rational. Those things are nasty.

04-08-08, 06:37 PM   #5
Alfster
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Quote:
 Originally Posted by jsharr Alfster, you are describing ground length of rainbow, but arch is dictated soley by pot of gold size. Once you know length and arch, then you are golden.
Yes, but the likely hood of you catching a Leprechaun to determine his pot of gold is slim-to-none. Therefore standard stride measurements were implemented to determine length. This will give the chord length of the arc. I thought everyone knew that

 04-09-08, 12:10 AM #6 CdCf Videre non videri   Join Date: Sep 2004 Location: Gothenburg, Sweden Bikes: 1 road bike (simple, light), 1 TT bike (could be more aero, could be lighter), 1 all-weather commuter and winter bike, 1 Monark 828E ergometer indoor bike Posts: 3,208 Mentioned: 0 Post(s) Tagged: 0 Thread(s) Quoted: 0 Post(s) The apparent size in terms of length and height in feet depends on how far away you decide to place it. The size measured in radians/degrees is an absolute number and fairly easy to calculate.
04-09-08, 12:12 AM   #7
Siu Blue Wind
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Oh forget all of the above hooey. Just ask Jon. He would know.
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 04-09-08, 12:14 AM #8 Pheard Banned   Join Date: Sep 2005 Location: South City, Ca Bikes: Posts: 3,348 Mentioned: 0 Post(s) Tagged: 0 Thread(s) Quoted: 0 Post(s) For every gay person it grows in length G(3*1.4x)
04-09-08, 12:21 AM   #9
iamlucky13
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 Originally Posted by Pheard For every gay person it grows in length G(3*1.4x)
Approximations are sloppy. More precisely it's G(3*sqrt(2)x).

Also, don't forget that the rainbow extends invisibly into the ultraviolet and infrared ranges. All you people are only considering the visible size of the rainbow.
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 04-09-08, 12:32 AM #10 Tude  Blasted Weeds     Join Date: Aug 2006 Location: Rochester, NY Bikes: Trek 1200C, Specialized Rockhopper, Giant Yukon FX, Giant Acapulco Posts: 1,182 Mentioned: 0 Post(s) Tagged: 0 Thread(s) Quoted: 0 Post(s) Foooey on Jon! I have Ze Truth!!! I've been taking my measured and calculated forefinger and thumb (my thumb btw is twice the size of Jsherr's - proven too) and have been seen around my area trying to measure using the "Crushy Your Head" theory. So far... I'm thinking that rainbow is no more than 2" high and 5" long. Does this help? If not, my Rainbow Crushy team is still on the road looking for new ones ... Oh and if you see any of us on the road and being chased by people ... can you deter them so we can continue our quest? Thank you.
04-09-08, 01:33 AM   #11
deraltekluge
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Quote:
 Originally Posted by East Hill No, I haven't lost my mind (well, not today at least). Mr. East Hill was musing today about how to calculate the apparent size of a rainbow. If this makes sense to anyone, could you please explain how to do this? East Hill
Google knows rainbows. Here's one place it found http://en.wikipedia.org/wiki/Rainbow

04-09-08, 01:50 AM   #12
maximan1
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Quote:
 Originally Posted by jsharr It is an algorithm based on the size of the pot of gold.
Pot of gold? Since when?

I always thought it was just pot.
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 04-09-08, 09:20 AM #13 deraltekluge Senior Member     Join Date: Sep 2006 Bikes: Kona Cinder Cone, Sun EZ-3 AX Posts: 1,195 Mentioned: 0 Post(s) Tagged: 0 Thread(s) Quoted: 0 Post(s) This pot of gold?
 04-09-08, 09:39 AM #14 trsidn  Inconceivable Member     Join Date: Jul 2007 Location: Putting the 'fun' in dysfunctional Bikes: Cannondale CAAD8, Trek SU200 Posts: 324 Mentioned: 1 Post(s) Tagged: 0 Thread(s) Quoted: 602 Post(s) __________________ We are all a litter of piglets in the barn fire of life - Piney McKnuckle
04-09-08, 09:47 AM   #15
Falkon
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Assuming it's a semi-circular rainbow, find the length between each end and multiply by by pi*d/2

Else, find the distance and height and derive a quadratic equation.
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 04-09-08, 10:06 AM #16 ItsJustMe Seņior Member     Join Date: Sep 2005 Location: Michigan Bikes: Windsor Fens, Giant Seek 0 (2014, Alfine 8 + discs) Posts: 13,739 Mentioned: 10 Post(s) Tagged: 0 Thread(s) Quoted: 412 Post(s) A primary rainbow will always subtend a 42 degree radius from a line from the sun through your head. I suppose if you insist on an absolute size, you need a distance, so it's however far the rain line is from you. I think the size is going to be 2 x distance x sin(42*) or about 1.3 x the distance from you to the rainbow (rain line) __________________ Work: the 8 hours that separates bike rides.
04-09-08, 10:34 AM   #17
USAZorro
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 Originally Posted by Tude Foooey on Jon! I have Ze Truth!!! I've been taking my measured and calculated forefinger and thumb (my thumb btw is twice the size of Jsherr's - proven too) ...
Wait. That means your is twice the size of his too. I didn't think you had a Tude.
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04-09-08, 10:48 AM   #18
jsharr
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everbody's is twice the size of my

I make John Wayne Bobbit look like a draught horse

This based solely on the highly scientific, post your thumb thread, which clearly showed that I have freakishly short digits.
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Quote:
 Originally Posted by colorider Phobias are for irrational fears. Fear of junk ripping badgers is perfectly rational. Those things are nasty.