A soap bubble in the sun plays with all the colors of the rainbow. Why?

When light hits the surface of a soap bubble, some of the light waves are immediately reflected. Some of the rest passes through the bubble wall, refracts in it, and then reflects off the inner surface. When these waves meet with waves reflected from the outer surface, their crests and troughs do not always line up in the same way. If the crests and troughs coincide, the waves amplify each other. If the crests and troughs do not match, the waves attenuate each other in a phenomenon called wave interference. As a result, a rainbow appears on the soap film, since the variable film thickness leads to the formation of interference patterns and light reflection in the form of rays of different colors with its own wavelength.