Advertise on Bikeforums.net



User Tag List

Results 1 to 18 of 18
  1. #1
    Lanky Lass East Hill's Avatar
    Join Date
    Sep 2005
    Location
    Take a deep breath, and ask--What would Sheldon do?
    My Bikes
    Nishiki Nut! International, Pro, Olympic 12, Sport mixte, and others too numerous to mention.
    Posts
    21,587
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(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...

  2. #2
    You Know!? For Kids! jsharr's Avatar
    Join Date
    Apr 2005
    Location
    Just NW of Richardson Bike Mart
    My Bikes
    '05 Trek 1200 / '90 Trek 8000 / '? Falcon Europa
    Posts
    6,117
    Mentioned
    12 Post(s)
    Tagged
    3 Thread(s)
    It is an algorithm based on the size of the pot of gold.
    Are you a registered member? Why not? Click here to register. It's free and only takes 27 seconds! Help out the forums, abide by our community guidelines.
    Quote Originally Posted by colorider View Post
    Phobias are for irrational fears. Fear of junk ripping badgers is perfectly rational. Those things are nasty.

  3. #3
    long time visiter Alfster's Avatar
    Join Date
    Oct 2005
    Location
    in the Northern Tundra
    My Bikes
    2005 Trek 6700 disc 2007 Orbea Onix 2009 Raleigh One Way
    Posts
    589
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(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.

  4. #4
    You Know!? For Kids! jsharr's Avatar
    Join Date
    Apr 2005
    Location
    Just NW of Richardson Bike Mart
    My Bikes
    '05 Trek 1200 / '90 Trek 8000 / '? Falcon Europa
    Posts
    6,117
    Mentioned
    12 Post(s)
    Tagged
    3 Thread(s)
    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.
    Are you a registered member? Why not? Click here to register. It's free and only takes 27 seconds! Help out the forums, abide by our community guidelines.
    Quote Originally Posted by colorider View Post
    Phobias are for irrational fears. Fear of junk ripping badgers is perfectly rational. Those things are nasty.

  5. #5
    long time visiter Alfster's Avatar
    Join Date
    Oct 2005
    Location
    in the Northern Tundra
    My Bikes
    2005 Trek 6700 disc 2007 Orbea Onix 2009 Raleigh One Way
    Posts
    589
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by jsharr View Post
    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

  6. #6
    Videre non videri
    Join Date
    Sep 2004
    Location
    Gothenburg, Sweden
    My 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
    3,204
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(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.

  7. #7
    Hey guyz? Guyz? Wait up!! Siu Blue Wind's Avatar
    Join Date
    Apr 2005
    Posts
    10,547
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Oh forget all of the above hooey. Just ask Jon. He would know.
    Quote Originally Posted by Buddha
    We are what we think. All that we are arises with our thoughts. With our thoughts, we make the world.
    Quote Originally Posted by making View Post
    Please dont outsmart the censor. That is a very expensive censor and every time one of you guys outsmart it it makes someone at the home office feel bad. We dont wanna do that. So dont cleverly disguise bad words.

  8. #8
    Banned
    Join Date
    Sep 2005
    Location
    South City, Ca
    Posts
    3,348
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    For every gay person it grows in length G(3*1.4x)

  9. #9
    Footballus vita est iamlucky13's Avatar
    Join Date
    Jun 2002
    Location
    Portland, OR
    My Bikes
    Trek 4500, Kona Dawg
    Posts
    2,118
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Pheard View Post
    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.
    "The internet is a place where absolutely nothing happens. You need to take advantage of that." ~ Strong Bad

  10. #10
    Blasted Weeds Tude's Avatar
    Join Date
    Aug 2006
    Location
    Rochester, NY
    My Bikes
    Trek 1200C, Specialized Rockhopper, Giant Yukon FX, Giant Acapulco
    Posts
    1,183
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(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... <squint> 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.

  11. #11
    Senior Member deraltekluge's Avatar
    Join Date
    Sep 2006
    My Bikes
    Kona Cinder Cone, Sun EZ-3 AX
    Posts
    1,195
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by East Hill View Post
    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

  12. #12
    Mr. Maximan1 maximan1's Avatar
    Join Date
    Sep 2006
    Location
    Anaheim and Fullerton (SoCal)
    My Bikes
    Puch Superleicht, Nishiki moutain project, Trek 2300 carbon composite
    Posts
    1,301
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by jsharr View Post
    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.

  13. #13
    Senior Member deraltekluge's Avatar
    Join Date
    Sep 2006
    My Bikes
    Kona Cinder Cone, Sun EZ-3 AX
    Posts
    1,195
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    This pot of gold?


  14. #14
    Grumpy Member trsidn's Avatar
    Join Date
    Jul 2007
    Location
    Putting the 'fun' in dysfunctional
    My Bikes
    Cannondale CAAD8, Trek SU200
    Posts
    234
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Mariah View Post
    Transcendental enumeration.

  15. #15
    The quieter you become... Falkon's Avatar
    Join Date
    Jan 2006
    Location
    Huntsville, AL
    My Bikes
    1973 Raleigh Superbe, 2006 Trek 4300 with no original parts, 1984 Ciocc, Custom Keith Anderson
    Posts
    1,283
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    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.
    Quote Originally Posted by TechKnowGN
    San Jose has to be the most boring place I've ever been. And I live in Ohio.

  16. #16
    Seņior Member ItsJustMe's Avatar
    Join Date
    Sep 2005
    Location
    Michigan
    My Bikes
    Windsor Fens, Giant Seek 0 (2014, Alfine 8 + discs)
    Posts
    11,819
    Mentioned
    6 Post(s)
    Tagged
    0 Thread(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.

  17. #17
    Seņor Member USAZorro's Avatar
    Join Date
    Oct 2004
    Location
    Carlisle, PA
    My Bikes
    1954 Hetchins M.O., 1959 Viking Severn Valley, 1970 Raleigh Pro, 1972 Fuji "The Finest", 1974 Raleigh Superbe&Comp, 1976 Raleigh Team Pro, 1994 Trek 830 MTB, 2000 Bob Jackson Arrowhead, Unicycle
    Posts
    13,034
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Tude View Post
    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.
    The search for inner peace continues...

  18. #18
    You Know!? For Kids! jsharr's Avatar
    Join Date
    Apr 2005
    Location
    Just NW of Richardson Bike Mart
    My Bikes
    '05 Trek 1200 / '90 Trek 8000 / '? Falcon Europa
    Posts
    6,117
    Mentioned
    12 Post(s)
    Tagged
    3 Thread(s)
    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.
    Are you a registered member? Why not? Click here to register. It's free and only takes 27 seconds! Help out the forums, abide by our community guidelines.
    Quote Originally Posted by colorider View Post
    Phobias are for irrational fears. Fear of junk ripping badgers is perfectly rational. Those things are nasty.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •