Or, in a related question, does the rainbow become apparent/disappear at some critical distance or weather conditions?
Note: The subject line is not specifically addressed to those on drugs.
Nothing…you can’t fly through a rainbow. You’ll always see it off in the distance, and as the angle you are viewing the rainbow from changes it will simply disappear, or seem to move away from you…or you might see a new rainbow. Two different people who have slightly different views wrt the angle they are looking at the light being refracted through moisture in the atmosphere might see different rainbows, or one might see it but another might not if the angle is a lot different wrt their perspective. I’ve actually seen this happen where one person says ‘do you see the rainbow’, and another says they don’t…until they come over and look from the the perspective of the first person.
Someone on the ground might see you flying, and from their perspective it might LOOK like you are flying through the rainbow, but it won’t look like anything to you.
As for the second part of your question, it has to do with the angle that light is passing through moisture in the air. IIRC, it’s something like 22 degrees view angle wrt the sunlight, but I might be misremembering.
-XT
Rain.
That is, you can’t see a rainbow except at some distance from you. Move towards it and it will move away or, eventually, disappear (for you). How far away it appears to be will depend. Most rainbows seem to be miles away, in my experience, but I have seen small rainbows in sprinklers, and on one occasion in actual rain, that appeared to be only a few feet away from me.
A rainbow doesn’t exist at any particular place, so you can’t go “through” it. It’s always off in the distance from wherever you’re looking at it. There is no area where the air is actually colored differently.
Like a bunch of leprechauns with a pot of gold.
It’s not so much that a rainbow is off in the distance, as that a rainbow doesn’t properly have a distance. It just has a direction.
Now, the drops which produce the rainbow do have a distance, and under the right conditions, that distance can be pretty close (most folks have seen rainbows from their lawn sprinkler, for instance). But from any other direction, those drops are just drops.
When seen from an airplane, a rainbow will be a full circle as opposed to the half circle seen from the ground. Per other posts, you can’t fly through a rainbow anymore than you can walk under one on the ground.
You don’t need to be in an airplane to get this effect. It’s not too hard to get a full-circle rainbow out of a sprinkler or garden hose, and I once saw a 270 degree natural rainbow from my 9th-floor apartment (though it was very faint).
The trick to finding rainbows, incidentally, is that the center of the circle will always be exactly in the direction of your shadow.
It looks like skittles. No wait, that’s what it tastes like. I have no idea what it looks like.
It’s certainly possible to see rainbows very close to you, not just “in the distance”. I vividly remember seeing one just outside my school about 20 years or so ago. I was on an area of grass with overhanging trees, and there was a fine drizzly rain falling. When the sun came out and shone between the trees, I could clearly see the end portion of a rainbow striking the grass a few feet in front of me. Of course, when I walked towards it, it moved and then disappeared, but I could definitely see “the end of the rainbow” on a patch of grass right before my eyes. No pot of gold, though.
I remember thinking at the time that ought to be impossible, but I have since seen similar effects near waterfalls when there’s a fine mist of water droplets in the air. I’m not sure exactly what factors affect the perceived distance of the rainbow.
Edit: I see njtt mentions a similar experience in actual rain. Glad it’s not just me! 
See also this great piece of journalism from the Daily Mail.
I wonder if he was driving northwards at about 20 to 30mph too? :smack:
The book For the Love of Physics has a very good chapter on rainbows that explains all of this (also discusses glories).
I once had the same experience as well, driving through heavy rain with low sun behind me. The rainbows were very close (in front of the trees on the opposite side of the road) and twice I actually approached one until I reached the point where it disappeared.
A long time ago my dad and I were going down the freeway in the rain and there was a rainbow in front of us. He insists that we not only drove through the rainbow, but that “inside it” everything was all rainbow colored. To my embarrassment he tells other people this too, and names me as a witness since I was there. When he does this I get really quiet and suddenly have a lot of things that I need to do which just won’t wait.
I don’t understand the physics of it but I drove through the base of a rainbow. It’s only happened once. I could see it at a distance and as I approached it I could actually see what appeared to be the end of it. It disappeared and reappeared as I turned a corner. The hood of my car was illuminated.
That would have been the same conditions under which I experienced. It was early in the year, later part of the day and I was driving North, North-East. The Sun was behind me and low.
Then something must be very messed up. 
Personally, since we as a nation must do something about this, I believe It’s The Joos. In fact, since I am a Jew and the OP, there’s proof positive right there.
Be that as it may, I am following this thread (for real), and am still thinking about some questions I will post shortly/
Try this experiment: Attach a spray nozzle to a hose and set it to as fine as mist as you can. Turn on the water on a sunny day. You should be able to see the rainbow in the mist. Carefully lower your face into the mist.
Send pictures.