Question

why can we see a bow shaped rainbow and pilot sees a complete circle

Answer 1

Because he is in the sky and so he can see thw full rainbow..actually rainbow is circled but we r on the ground thats y we see it bow shaped

Answer 2

Answer:-

In theory every rainbow is a circle, but from the ground only its upper half can be seen. Since the rainbow's centre is diametrically opposed to the sun's position in the sky, more of the circle comes into view as the sun approaches the horizon, meaning that the largest section of the circle normally seen is about 50% during sunset or sunrise. Viewing the rainbow's lower half requires the presence of water droplets below the observer's horizon, as well as sunlight that is able to reach them. These requirements are not usually met when the viewer is at ground level, either because droplets are absent in the required position, or because the sunlight is obstructed by the landscape behind the observer.

But you can also see it by spraying water with the sun behind your back.