I am not a genius. I learned it from standard textbook for physics. If you have enough resolution device, you even can see the third ranibow. But it will be very difficult, because the first two are pointing back to the direction of the sun, so you can see it while your back is face to the sun. (for the light coming from the sun, the intensity of the rainbow light will be too weak compared to the light from the sun, so you would not be able to see it).
Intensity for the second rainbow is even weaker(2%) than the first one (about 5% of the intensity of sun light).
So normally, you might not notice it.
If you drag the horizontal red line with your mouse from the top and move it downward slowly.
Check out the angle for #3 ray (at the bottom you will find 3):
you will find the angle increase first, then at about 42 degree it become smaller again as you continue to drag the line down.
And the maximum angle is the angle you will find rainbow for red light (when the ray of incoming sun light is horizontal).
You will find #4 ray at the top. But when you drag the red line lower than the center of the water drop(big white circle)
the # 4 ray starts to point download. when it reach near 50 degree(also the maximum angle), that is the angle you will find the second rainbow.
Normally, when you watch the rainbow, the ray of the sun light is not horizontal.
If it is 15 degree higher, you need to substrate the 15 from 42 (or 50). So when the sun is too high, there is no way you will find rainbow in the ground (you might see rainbow from high enough mountain).
So you might be able to see the rainbow in the early morning or late in the afternoon.
I hope the above information will help. I upload the picture for the rainbow, so more user can see the beautiful rainbow.
And I hope many of you can enjoy the fun of physics as I do.