Is the sky really blue?(Kumiko Shimizu / Upsplash)This week on Science Behind the Forecast, hear why the sky isn’t blue. Seriously. LPM’s Bill Burton talks about why with meteorologist Tawana Andrew.This transcript was edited for clarity and length.Tawana Andrew: Are you ready to have your min d blown?Bill Burton: I am definitely ready for this. This is one of the more unusual topics that we've tackled during Science Behind the Forecast, and we really are going to be messing with everybody today because we're going to spend a little time talking about why the sky that you see every single day and you're confident of its color, is not really blue after all.TA: Yes, I know you look up and you see it, it's blue. But technically it's all a lie. Let's break down why. I'm sorry in advance, but technically, it's all a lie. That's right. All the white light from the sun is a combination of every single color in the rainbow, and each of these colors corresponds to a particular wavelength. The visible light spectrum ranges from violet, which is a pretty short wavelength of around 380 nanometers, to red, which has a wavelength of around 720 nanometers. All of the particulates and gasses in our atmosphere help to scatter the sunlight, and because of its shorter wavelength, violet light is scattered first, very, very high up in the atmosphere. That's all gone pretty quickly. Next, we have the indigo light waves that are scattered, and then that is followed by the blue. The molecules in our atmosphere actually scatter blue light around four times as much as they do red light. But, technically, violet light is scattered the most, so the sky is actually a bluish violet. Soak that in first.BB: I'm trying to absorb it. I'm trying.TA: The sky is blueish violet. So the question is, why don't we see the sky as purple? Our biology is the reason that we see the sky as blue. We have color-sensitive cones in our eyes that react most strongly to blue, green, and red wavelengths. This is why we see colors the way we do typically. Blue and violet react not just with the blue cones in our eyes, but they also interact with those red and green cones that we have. That means that when our eyes see that slight reddish tinge to the violet and that slight greenish tinge to blue, our eyes basically negate that, just wipes it all out, and that is why we just see the blue sky. But it's technically bluish purple.BB: Technically, it's bluish purple. So Prince was onto something with Purple Rain.TA: He knew what he was talking about.BB: I'm not sure there wasn't anything Prince couldn't do, including meteorology.TA: He's not wrong. He has never been wrong. ...read more read less