Why is the sky blue?

ArabiaWeather - Why is the sky blue? This beautiful and distinctive blue color that humans see in the sky is a natural mystery that arouses the curiosity of many.

The color of the sky is a phenomenon that requires a reasonable scientific explanation. However, ideas and explanations continue to attract human minds. In this article, we will dive into the world of sky color, reveal the scientific reasons that make it blue, and delve deeper into the physical nature of this wonderful phenomenon.

Common beliefs about the blue color of the sky

For a long time, there were different perceptions indicating the reason for the blueness of the sky , and one of these perceptions indicated that the sky appears blue due to the reflection of sunlight from the surface of the ocean and its return to the sky, but this perception cannot explain why the sky appears blue in areas far from the sea. Like green fields. There is another perception that indicates that the blueness of the sky is caused by the dissipation of light when it collides with water droplets in the atmosphere, but this perception cannot explain why the sky appears blue in dry areas such as the desert. So, what is the real reason behind the blue color of the sky?

What is the real reason behind the blue color of the sky?

Answer: The possibility of answering this question lies in the source of lighting in our solar system, i.e. the sun . Although solar light appears white to the naked eye, in reality it consists of a multi-colored spectrum extending from red to violet and what makes the sky appear blue is Interaction of solar light with the atmosphere.

We can conclude that light moves in waves , and each color in the spectrum has a specific wavelength. Warm colors like red have longer wavelengths, while cool colors like blue and violet have shorter wavelengths.

In addition, light interacts in different ways with the materials it passes through. For example, when solar light passes through a transparent substance such as water, the light is refracted as a result of its speed changing as it moves from one medium (such as air) to another (such as water). This leads to To the deflection of light waves, and with regard to other materials, such as mirrors, these materials reflect light in one direction without scattering it, and there are other materials that scatter light in multiple directions.

So, the source of light and the way light interacts with materials play a crucial role in shaping the colors and optical phenomena we see in our daily lives.

Why do we see the sky blue?

When sunlight reaches the Earth's atmosphere, the light is scattered or deflected by tiny gas molecules in the air, which are mainly dominated by nitrogen and oxygen molecules; The process of scattering light in the atmosphere depends on the wavelength of the light and the size of the substance that scatters it. This process is known as Rayleigh scattering, and it is named after Lord Rayleigh, the British physicist who discovered it.

What is Rayleigh scattering and what is its relationship to the blue color of the sky?

Rayleigh scattering is the process that causes light or electromagnetic radiation to be scattered by particles whose radius is one-tenth of the wavelength of the radiation.

Gas molecules in the air, such as hydrogen, which represents 78% of the atmosphere, are much smaller than the wavelength of visible light, about a thousand times, and oxygen and nitrogen molecules in the lower layer of the atmosphere absorb shorter wavelengths, such as blue and violet, and scatter them. In all directions, while the red color, which has a longer wavelength, passes without being scattered and reaches the surface of the Earth.

However, the sky at noon appears blue, not violet, because our eyes are more sensitive to blue , and also; Because violet light has great energy, it has the ability to be absorbed more by gas molecules in the upper layers of the atmosphere. Due to this process, blue light in the sky causes a predominance over violet light. At the same time, tiny particles scatter the blue light transmitted from the sky through The atmosphere, allowing us to see the sky as blue when looking up, away from the sun.

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Sources:

aljazeera

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