We went to the Greenbelt Festival on Cheltenham Racecourse. They had set up flags in the grandstand seats. I imagine it shows that the festival covers the whole spectrum. What I liked was that they used more than the traditional 7 colours. I have heard it said that Isaac Newton was superstitious about numbers and wanted 7 colours because 7 is the perfect number. So if you've ever wondered why you find it hard to see the differences between blue, indigo and violet... The spectrum shown above is arguably more realistic. I also liked it that the wind only ruffled the flags in certain seats, showing a complex air flow around the stand. If I ever get to watch the races from the grandstand, I'll choose one of the seats that was calm.
