Blue emergency lights

September 1, 2010 at 4:06 pm • Posted in ALL POSTS, Law Enforcement, Science270 Comments

Years ago, the Washington State Patrol switched from red flashing lights to blue lights at a heavy cost to the taxpayer. I don’t remember the justification given, but I thought it was a waste of money at the time. Recently I thought back to a demonstration of the Tyndall effect that my physics teacher in high school showed us in class. It demonstrated that light passing through a medium with suspended particulates will be reflected and refracted depending on its wavelengths. As the particulate per unit volume increases, the shorter wavelengths of light (blue) are scattered back and dispersed while the longer wavelengths of light were still transmitted through the medium. Simply stated, the last color to be filtered out is red (The longest wavelength in the visible spectrum). This is why we observe red sunsets rather than blue sunsets when there is dust, smoke, or some other source of particulates in the air.
Red was always the best color for emergency lights. Someone should be required to repay the taxpayers of Washington State for that boondoggle. (Note: Now you know why you don’t see blue lights used on aircraft.)