Is there a proper term for the swirly rainbow patterns you see on the oily film on puddles, soap bubbles, etc?
Iridescence
ETA, if you want to impress your friends, it’s specifically thin film interference and has to do with how light interacts with itself after bouncing off the top and bottom of the oil.
that is correct.
a common term that is often used is oily sheen, though just a descriptor of its beauty.
Even more specifically, oil lms and soap bubbles are examples of white light thin film interference. You only see this for very thin films, since white light has a very small coherence length. You don’t really get all colors with such films 00 yellow shows up for very thin films. You don’t really get pure red or green. After the first order or two, the films show up as alternating bands of turquoise and pink-violet. These are the most common colors in soap bubbles. They also show up in the “supernumerary” rainbow bands you can sometimes see.
http://www.exploratorium.edu/ronh/bubbles/bubble_colors.html
Thanks everyone 