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Rayleigh scattering is the phenomenon by which we think the sky is blue.
Imagine you are in Antarctica. Your eyes meet the sky, and the blue is so vivid it seems electric. The air is so clean you can almost taste it.
Now, imagine a dust storm over the Himalayas. He squints, trying to catch a glimpse of that crisp blue, but all he sees is a fuzzy white.
After all, why are the skies in some parts of the world bluer than in others?
A The color of the sky has always been easy to admire, but even easier to ignore. However, scientists are discovering that it is much more significant than we ever assumed. It’s a visible record of what’s floating in the air around us.
In reality, the blue color of the sky is the result of a fascinating phenomenon that scientists call Rayleigh scatteringin which electrons in air molecules such as nitrogen and oxygen are stirred by the oscillating electric field of light as it passes through the atmosphere.
As explained by , these oscillating electrons re-emit light in all directions – and the faster they are accelerated by sunlight, the more light they radiate.
Because shorter wavelengths oscillate at higher frequencies, causing electrons to accelerate faster, violet and blue are the colors that tend to stand out more.
“Why isn’t the sky violet, then?”some readers will ask (quite rightly). Technically, it is.
O violet has an even shorter wavelength than blue and therefore disperse more – but some of it is absorbed in the upper atmosphere. Furthermore, the human eye is more sensitive to bluetherefore, to our eyes the sky appears blue.
However, when the air is “loaded”, so to speak, with larger particles (aerosols) such as moisture, soot and smoke, a different type of scattering occurs, known as Mie scattering.
When light encounters these larger particles, they do not react as single points – different parts of the particle respond to different points in the incident wave, creating a much more complex pattern of scattered light. In this case, the different wavelengths of sunlight are dispersed more evenly, causing the sky appears white and misty. This is why clouds, made of tiny water droplets, appear white.
A 2023 study in Nature he discovered that when desert dust mixes with pollutants, larger particles scatter light over a wider range of wavelengths, and the result is a sky that appears hazy white.
Refractor writes that the beautiful blue color of our sky is not just a pleasing aesthetic issue, but is often a air purity signand a consequence of what floats in it invisibly.
