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Is it physically possible to drive through a rainbow? Why or why not?
A rainbow does not actually exist at a location in the sky, but is an optical phenomenon whose apparent position depends on the observer's location. All raindrops refract and reflect the sunlight in the same way, but only the light from some raindrops reaches the observer's eye. These raindrops are perceived to constitute the rainbow by that observer. Its position is always in the opposite direction of the sun with respect to the observer, and the interior is slightly brighter than the exterior. The bow is centred on the shadow of the observer's head, or more exactly at the antisolar point (which is below the horizon during the daytime), appearing at an angle of approximately 40°–42° to the line between the observer's head and its shadow (this means that if the sun is higher than 42° the rainbow is below the horizon and cannot be seen unless the observer is at the top of a mountain or a similar vantage point).
When the rain is uniform, the rainbow that you see is a cone with your eye in the apex. So you will never have the impression of approaching the rainbow, because it always extends from your eye to very far away.Neveos said:As we got closer, we realized that we might actually approach, what appeared to be, the end of the rainbow.
When you get into light rain that sprays your windows with tiny water drops, with the sun low, you will see a lot of nice color effects. (However, this can be annoying when you are trying to land a glider, which don't have wipers.)Neveos said:The interior of the car became very bright, and it did, in fact, change colors all around us. I vividly remember my arm lighting up as though it were being shined upon by a sequence of colored lights.
It was a bit more distinct than this to my memory, however I do not discount the possibility of wishful thinking playing a role in what I saw. I'm not willing to discard what I vividly saw, which was the colorization of the interior. There are actually a lot of videos surfacing on youtube of people getting close to the foot of rainbows, so it seems to have happened enough times to accrue a number of eyewitness accounts. A lot of other people are saying they witnessed a change in colors as well. However, from the videos, it does appear that it is less manifestation than I thought, so I am inclined to believe that I am wrong. However, being able to "pass" and "approach" a rainbow, to the degree that one is capable of is quite different than one would expect from messing with standard rainbows made in a mist.When you get into light rain that sprays your windows with tiny water drops, with the sun low, you will see a lot of nice color effects. (However, this can be annoying when you are trying to land a glider, which don't have wipers.)
Link some that are similar to what you saw.Neveos said:There are actually a lot of videos surfacing on youtube
That is no problem as I decribed above. In fact, once you drive into the rain, the foot of the rainbow (intersection of the cone and the ground) starts right outside of your car.Neveos said:of people getting close to the foot of rainbows,
The water drops that send light of a certain color to your eye have a well defined position. They form a cone surface with your eye in the apex, and an axis patallel to the sun rays.sophiecentaur said:A rainbow is a virtual image that is not, actually, anywhere.
Not really. It will appear where the water drops are. It can extend from your position to a few kilometers away.sophiecentaur said:Mostly (when in the sky) it will appear to be at infinity.
It doesn't just appear to be in front of a distant hill. It is in front of it, if the rainy area is closer than the hill.sophiecentaur said:But it can often appear in front of a distant hill
Whether it extends beyond the hill depends on whether it also rains behind the hill. So the brain might sometimes be right here.sophiecentaur said:(your brain tells you that it can't be behind the hill!)
The term "virtual image" makes no sense in the case of a rainbow, because there is no focused virtual image of the sun, like in the case of a simple mirror.sophiecentaur said:The mirror that you gaze at yourself in also has a defined position, on the wall. That doesn't mean that your (virtual) image appears in that position.
And neither is a water droplet a simple mirror. And a single water droplet doesn't produce a rainbow, the collective of many water droplets does. And within that collective there is a subset for each each color which forms a cone. It's that cone determines where you see the rainbow, not some "virtual image" of the sun.sophiecentaur said:The mirror is not a projector screen and neither is a water droplet.
There is focussing involved in seeing anything. That is why your eyes have lenses.sophiecentaur said:There is no focussing involved in order to see a virtual image.
Yes, assuming a spherical raindrop the real image for the reflection on the inner surface is in the raindrop. (I had a typo in my previous post, calling it "virtual"). But the key point I was making is, that there is no distinct virtual image here.sophiecentaur said:My issue is that you are claiming that there is an image 'in' the raindrops
What is nonsense, is your claim that a virtual image is somehow produced here. A concave mirror cannot produce a virtual image of an object which is placed outside of the mirrors focal length.sophiecentaur said:This is nonsense which you will discover (using schoolboy ray tracing) when you try to draw a diagram of what goes on. When you have failed, take a look on Wiki or any of the other explanations you can find.
A.T. said:Each water droplet produces a real image of the sun (for each color), within the droplet itself. But that image is quite irrelevant seeing the rainbow.
I made it pretty clear that the real image inside the raindrop is not relevant for seeing the rainbow. The only reason I even mentioned that image is because you claimed that we see a virtual image.sophiecentaur said:Can you point our where, in the raindrop diagram, there is any focussing of a real image that you could possibly see?
There is no virtual image at all here. Concave mirrors don't create virtual images of objects that are outside of their focal length:sophiecentaur said:I don't claim that a virtual image is formed in the drop.
The sun is hardly inside the focal length of a raindrop.hyperphysics said:Concave Mirror Image
If the object is outside the focal length, a concave mirror will form a real, inverted image.
If an object is placed inside the focal length of a concave mirror, and enlarged virtual and erect image will be formed behind the mirror.
You brought up the concept of "virtual images" which is not relevant here. I just pointed out that the only image here is inside the drop and I said that it is not relevant right in the same post.sophiecentaur said:My problem with reading your posts is that you bring up ideas and then say they are not relevant.
The term "virtual image" that you originally used has a specific meaning which not applicable to a rainbow.sophiecentaur said:I'm afraid the whole point about a rainbow is that it is virtual.
Wrong. The first occurrence of the word "image" in this thread is in your post:sophiecentaur said:It is you who first introduced the idea of focussing and image formation.
sophiecentaur said:A rainbow is a virtual image...
Too vague. Try this:sophiecentaur said:an image as 'something you can see'.
It implies 'not even wrong'. Get back to me when you have drawn the diagram showing how a virtual image is formed for a rainbow.sophiecentaur said:"Vague" doesn't imply 'wrong' in any case.
You continuously ask me to to show some things, that I never claimed. If you have a question about something that I actually wrote, quote my statement, explain how you understand it and your objection to it. (Just as I do with your statements)sophiecentaur said:I actually asked you first to show me a proper diagram showing your argument
Every water droplet creates a cone of reflected 'red' rays, which are not all parallel. The red rays that form the red arc in the eye also obviously not parallel, because have to cross in the eye. So which red rays are "all parallel" again?sophiecentaur said:That means that the 'red' rays (of around the same wavelength) are all parallel.
No. Not even the rays reflected by one single drop of the same color are all parallel. They form a cone with the drop in the apex and the line drop-sun as axis.sophiecentaur said:the rays of the same colour from adjacent drops are parallel.
sophiecentaur said:You wanted a quote from one of your posts: Part of Post 7:
"
The water drops that send light of a certain color to your eye have a well defined position (DIRECTION, ACTUALLY). They form a cone surface with your eye in the apex, and an axis patallel to the sun rays.
. . . . . .
It will appear where the water drops are. It can extend from your position to a few kilometers away.
.. . . .
It doesn't just appear to be in front of a distant hill. It is in front of it, if the rainy area is closer than the hill. "
That's what I wanted you to justify.
That's completely backwards. If all rays for one wavelength that hit your eye were parallel, you would not see a bow, bur rather a point in the distance.sophiecentaur said:There is only one direction for one wavelength. That is why the bow appears at all.
Quote my statement, ask a question about it or explain how you understand it and give your objection to it.sophiecentaur said:Are you saying that you cannot justify your statement(s) in that quoted post?
Not really. You fail to point out what you think is wrong with my statements, or how you understand (or misunderstand) them. When I have a problem with something you said, I try to clarify it. For example:sophiecentaur said:You understand perfectly well what I want.
What exactly do you mean by "all" here?sophiecentaur said:That means that the 'red' rays (of around the same wavelength) are all parallel.
That's just a semantical issue. When explaining the phenomenon that the OP described (apparently approaching the base of the rainbow) it is practical to consider the intersection of the volume that currently reflects light into the eye with the ground and other obstacles. If you don't like calling that volume the "rainbow" as I did for simplicity, that is fine with me. We can call it something else.sophiecentaur said:your statement that the rainbow 'is' where the drops are, is wrong.
You were not even able to say how you technically define "image" here. You didn't like the http://en.wikipedia.org/wiki/Virtual_image" but provided no alternative reference nor a diagram showing how it applies to a rainbow.sophiecentaur said:I have told you a good reason for saying that the image ...
See above. The grounds is the intersection of the volume that currently reflects light into the eye with the ground and other obstacles.sophiecentaur said:I am asking you for the grounds to justify that bit in bold, in the earlier post.
No, that's not what it means. "Deviated exactly the same amount" means that they all have the same angle to the incoming sun rays. So for each drop they form a cone with the drop at the apex, that opens towards the sun. Rays forming a cone are not all parallel to each other.sophiecentaur said:Red rays of the same wavelength (say 800nm) are deviated exactly the same amount by all water drops.That means that they will all be parallel to each other.