It is pleasant to look in the blue sky is dazzling or to enjoy a crimson sunset. Many people with pleasure admire beauty of the world around, but not everyone understands the nature of what they observe. In particular, it is difficult for them to give the answer to a question why the sky blue, and a sunset red.
The sun radiates pure white light., It seems, and the sky has to be white, but it seems bright blue. Why does that happen?
Scientific several centuries could not explain blue color of the sky. From a school course of physics all know that white light by means of a prism can be spread out to the colors which are it. For their storing there is even a simple phrase: "Each Hunter Zhelayet Znat, Where the Pheasant Sits". Initial letters of words of this phrase allow to remember an order of flowers in a range: red, orange, yellow, green, blue, blue, violet.
Scientists assumed that blue color of the sky is caused by the fact that the blue component of a solar range best of all reaches the Earth's surface whereas other colors are absorbed by ozone or the dust disseminated in the atmosphere. Explanations were rather interesting, but they were not confirmed by experiments and calculations. Attempts to explain blue color of the sky did not stop, and in 1899 lord Rayleigh put forward the theory which at last gave the answer to this question. It became clear that blue color of the sky is caused by properties of molecules of air. Some quantity of the beams going from the Sun without hindrances reaches the Earth's surface, but their main part is absorbed by air molecules. Absorbing photons, molecules of air are loaded excited) and already let out photons. But these photons have other wavelength, at the same time among them the photons giving blue color prevail. For this reason the sky looks blue: than more solar costs day and than less overcast, especially saturated becomes this blue color of the sky. But if the sky blue then why during a sunset it is painted in crimson tone? The reason of it is very simple. The red component of a solar range is much worse absorbed by air molecules, than other colors. In the afternoon sunshine enter the atmosphere of Earth at an angle, directly depending on the width at which there is an observer. On the equator this corner will be close to direct, to poles it will closer decrease. In process of the movement of the Sun, the layer of air which light beams should pass before reaching the observer's eye, increases – the Sun not over the head any more, and tends to the horizon. The thick layer of air absorbs the main part of beams of a solar range, but red beams reach the observer almost without loss. For this reason the sunset looks red.