Green laser in the sky

How come when you shine a green laser in the sky the beam just seams to stop after a certain distance?

It runs out of air, dust, smoke etc.
Also it's afraid of heights ;D

Mike

laugh out loud

I've noticed that too like when I shine my rpl165 in the sky it seems like it's only a 100' long till the beam hits something far away then it looks super long. it's an optical illusion called spacial sensory deprevation.  ;D

Thanks for the info, also what does RPL stand for?

popo_police said:

Thanks for the info, also what does RPL stand for?

Click to expand...

Rockin Party Laser ;D

popo_police said:

How come when you shine a green laser in the sky the beam just seams to stop after a certain distance?

Click to expand...

You could also ask, "why do railroad tracks seem to come to a point" Same thing

popo_police said:

Thanks for the info, also what does RPL stand for?

Click to expand...

RPL's are made by optotronics, www.optotronics.com/ check em out.  

popo_police said:

Thanks for the info, also what does RPL stand for?

Click to expand...

Rechargeable Portable Laser

all the way til u cant see it... but this is with fog n it stopped once it hit the cloud..

daguin said:

[quote author=popo_police link=1230840928/0#4 date=1230913670]Thanks for the info, also what does RPL stand for?

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Rechargeable Portable Laser[/quote]

I thought it was "Really Powerful Laser"...

-Mark

To answer the original question: The air contains tiny floating particles of dust/debris called "aerosols". The aerosol layer is really only a few thousand feet high, if that. Beyond that there is not nearly as much debris, so consequently the beam becomes much less visible. The purity of the air increases with altitude, so the higher you go, the less you can see the beam. No matter how powerful the laser, the beam will appear to end at the same height no matter what the viewing perspective.

I've also wondered about that.  I found a website that explains the reason that the beam appears to end:

"So why DOES that beam of light simply stop at the target, instead of fading out in the distance, or seeming to go on "forever". Well, the answer's obvious if you do the math. If the laser is one foot away from my eyes, to the side, and I'm looking towards the "end" of the beam, then we can start to think in triangles, where the base is 1 foot long. If I look at a point 100 feet along the beam, then we have a tall skinny triangle with sides of 1 foot, 100 feet, The small angle for this triangle is 0.57 degrees. That's the angle between my sight line and the laser beam. But that means that the other angle is 89.42 degrees. The first 100 feet of beam covers 89.42 degrees of view to my eye. Let's look a thousand feet down the beam. We now cover 89.94 degrees of our field of view. Going ten times farther filled an additional 0.37 degrees of our field of view with a beam. At 10,000 feet, we get to 89.99 degrees - and we gained 0.05 degrees or three arcminutes. Beam-of-light technologies claims their beam from this product reaches 25,000 feet. If that's the case, then the additional 15,000 feet past what we just calculated will add 0.003 degrees to our view of the beam, or 10 arcSECONDS. "

"The first 10,000 feet gives us a laser beam across almost 90 degrees of our view. And the next 15,000 feet of beam visually lengthens the visible beam by a size smaller than the disk of Saturn, Jupiter, or Venus. In other words, while the beam is fading out gradually, the part of it that we can actually see, the close part goes almost all the way to where we're pointing, while the long long section that fades out, adds almost no visible length to the beam. Even the section of the beam starting after one thousand feet away only lengthens the visible beam by the size of a crater on the moon that's too small to see with the naked eye. "


I'd post a link to the source, but the forums won't let me since I haven't made enough posts.  It's at hea-www dot harvard dot edu/~fine/opinions/z-bolt-6plus.html

I couldn't of said it any better myself. It's all about perspective. That far away you are actually looking through the beam making it seem to stop. It's like looking at the but of a pole with it lined up with your eye sight. All you can see the the end closest to you and the rest is hidden from view behind that point.

I'm not sure how accurate that explanation is. Here's a link that will help answer this: http://calgary.rasc.ca/atmosphere.htm

Your explanation explains the maximum distance the beam can travel in general. The question was asking about the fact that humans perceive the beam as ending much sooner than it actually does.