One of my favourite types of FlowViz that you can see yourself, even when simply walking down the street, is that given by oil sheens. These can often be seen in the flow in gutters after a rainstorm. (Not that I spend my time looking around in gutters)
Similarly to bubbles the multitude of colours that can be seen in today’s picture comes from thin-film interference. Interference between light reflecting off the top of the oil and the top of the water underneath causes the colours we see. The colour seen depends on how thick the film is at that point.Also, please reblog/retweet the first video from today. FYFD is basically the reason I started writing my blog and even if I only get a few extra people to see the video that might well help.