If viewed from a high place, such as from an airplane, the rainbow can be seen as a full 360 degree circle, but if you are sitting on the ground, the low viewing angle makes the rainbow appear to be a half circle.
If viewed from a high place, such as from an airplane, the rainbow can be seen as a full 360 degree circle, but if you are sitting on the ground, the low viewing angle makes the rainbow appear to be a half circle.