Air Force blue colours are a variety of colours that are mostly various tones of the colour azure, the purest tones of which are identified as being the colour of the sky on a clear day. Some air force blue colours, notably the air force blue colour used by the United States Air Force and the colour used by the US Air Force Academy, may look like they are tones of blue instead of azure (On the RGB colour wheel, which has 12 major colours, blue is the colour at a hue code of 240 degrees and azure is the colour halfway between blue and cyan at a hue code of 210 degrees.). However, they are actually dark tones of azure, not blue, because their hue (h) codes are between 195 and 225, the signature of a tone of azure.