Interference on a soap film

We have created these soap films using the same solution as for the huge bubbles. The colours are the result of interference - a composition of light waves reflected from the front and rear sides of the bubble. Thanks to interference one can tell what is the thickness of the membrane at a given place. There can occur even a liquid flow within the membrane (e.g. when we blow on it) which results in interesting structures. Comparing the first three pictures that were taken a few seconds after one another, one can see that the liquid flows within the film and that evaporation takes place.