The color of the sky

How many different colors do colored things around us? Science can already give an answer to such questions. For example, science can explain the color of the sky.

Science can explain the color of the sky

First you need to mention the great Isaac Newton observed the decomposition of white sunlight as it passes through a glass prism. What he saw, we call the dispersion. Colorful pattern called the spectrum. The resulting colors match exactly the colors of the rainbow. That is, Newton saw a rainbow in the lab! Thanks to his experience in the late 18th century, it was found that white light is a mixture of different colors. Newton showed that if a variety of colors to mix again, you get white light. In the 19th century, it was shown that the light is an electromagnetic wave propagating at a speed of 300000 km/sec. At the beginning of the last century, these were supplemented by the knowledge of the idea of a quantum of light, i.e. photons. Thus, the light has a dual nature of waves and particles. This association was the explanation of many phenomena, in particular, the spectrum of the thermal radiation of heated bodies, such as our sun.

Let's go back to our object. The blue color of the sky... Who has not admired him at least a couple of times! Can we say that all the fault of the light scattering in the atmosphere? Why is the sky not blue in the light of the full moon? Why the color blue is not the same in all parts of the sky? What happens to the color of the sky at sunrise and sunset? After all, it can be yellow, pink and even green. Let us consider the features of the scattering of light in detail.

For the first time managed to explain the color of the sky english physicist John Rayleigh. It was he who pointed out that the color of the sky is determined by the scattering dependence on the frequency of light. Radiation from the sun interacts with gas molecules in the atmosphere. These gases are in the air composition. If the photon energy increases with decreasing wavelength of light, the most profound effect on the gas molecules have photons of blue and violet light spectrum. Excited electrons of molecules is given in the form of a photon of light taken from wave energy. These secondary photons are emitted in all directions already. This process is called scattering. In addition, it is necessary to consider constant movement of air and its density fluctuation. Otherwise, we would have seen the black sky.

Let's go back to the thermal radiation of bodies. Energy in its spectrum is distributed unevenly and is described on the basis of the laws established by the German physicist Wilhelm Wien. The spectrum of the Sun will be uneven for photon energies. Photons violet part of the solar spectrum would be much less than the photons of blue and blue parts. Taking into account the physiology of vision, that is, the maximum sensitivity of our eyes to blue-green color, we get as a result of sky blue color.

Taking into account the physiology of vision, that is, the maximum sensitivity of our eyes to blue-green color, we get as a result of sky blue color

The longer the path of the sun's rays in the atmosphere, the less it remains noninteracting photons of blue region of the spectrum. Therefore, the color of the sky is uneven. Morning and evening the color of the sky become yellow and red because of the great path of light through the atmosphere. Additionally, dust, smoke and other air particles strongly influence the dispersion of light in the atmosphere. In support of this, we can recall the famous London paintings by Claude Monet. But these effects are attributed to a different theory. This theory suggested the german physicist Gustav Mie. This theory shows that the relatively large size particles scatter red light more than blue and purple.

Thus, the color of the sky is not just a source of inspiration for poets and artists. The color of the sky is a result of subtle physical laws.