Rainbows are spectacular things. But I imagine why we can't reach to the ends of rainbows. Do rainbows have no ends ? If so, why can't we reach at them? If you go closer,they will go further. Why?
[Physics] Why can’t we reach the ends of rainbow
everyday-lifeopticsreflectionrefraction
Related Solutions
After some search, I found a video on youtube which was about the rainbow.It says that
The set of all points which have a fixed angle between the sunlight, the raindrop and the observer creates the circular arc of the rainbow.
This picture helped me.
For the second question about the reason that we just see a special color at each angle, I watched Lewin's lecture at Delft University of technology.He mentioned the reason and said
At the maximum values of $\varphi$, there is a peak in the intensity of that special light.
Because of that, although all colors exist at e.g.$40.7^\circ$ but just one color is seen because the peak intensity of blue occurs at $40.7^\circ$ .
You are right. Rainbows can occur all over the sky. However the traditional one and two internal reflections of the primary and secondary bows send light back towards the sun and hence their bows appear opposite the sun and centered on the antisolar point. The reflection of the main light makes these bows stand out.
And only the light that enters a droplet is reflected in some manner. Sometimes it is a single reflection and you get a primary rainbow which everyone is familiar with. Depending on how dense the droplets are some light will pass through all the drops and will not be reflected creating a hazy or dim rainbow.
If some of the light bounces inside the droplet (enters but does not exit and bounces inside twice more) you'll see a weaker double rain bow caused the the light that has bounced 2 times.
So there are many orders of rainbows:
A zero order is when there are no internal droplet reflections and the droplet is sun ward. This creates an orange shifted glow.
There must be some radiation refracting from inside the droplet to the air: since different wavelengths refract through different angles, shouldn't we also see a rainbow when the Sun is in front of us?
The width you see of the rainbow represents the spreading of the frequencies and their slightly different refraction angles. Light can be refracted in many different ways from the droplets with the sun in between you, but they don't form the traditional bow shape which has to do with the arc of the sun being behind you and refracted back. This is mostly because the suns brightness make it too hard to see.
And here are some other refraction examples that are not really considered rainbows.
Take a look at this site for more about atmospheric optics.
Best Answer
The WIkipedia article you linked to contains the explanation
The primary rainbow is refracted at an angle of 42 degrees. If you are at an angle of say 52 degrees from some droplets you won't see any light refracted by those particular droplets.
As you walk 1 meter towards the droplets that are refracting the rainbow you initially see, you move outside the the "beam" from those specific droplets and move into the "beam" refracted by droplets 1 m further back.