The colour of the sky

The sky’s colours can be breathtaking. Shades of red, orange, blue, and even purple can be observed practically every day, whether in the clouds or the sky. Do you know why the sky is constantly changing colours?

Why Is the Sky Blue?

Sunlight is made up of all the colours of light. It appears as white light when all the colours are together. Sunlight travels as waves of energy, and different colours of light have different wavelengths. Red light has long wavelengths, while blue light has short wavelengths. Light bounces off of air molecules in the Earth’s atmosphere, scattering in all directions. Blue light is scattered more than other colours of light because of its shorter, smaller waves. Because blue light is scattered more than other colours of light, the sky appears blue.

Why Is The Sky Red?

The sky normally turns red during a sunset, and to a lesser extent, sunrise. At this time, the sun is either touching or just beneath the horizon.

Due to the position of the sun, the light has to travel much further through the atmosphere to reach your location. As always, violet and blue light are scattered the most, lighting up the sky below them. However, you are now much further away from the sun and scattered light.

With many more molecules in the air to travel through, the blue light gets scattered and rescattered and fades long before it reaches you. Red light, which has a longer wavelength, travels unaffected through the particles to reach you, making it possible to view.

If the sky is polluted, more particles are present in the atmosphere, which means even more shortwave colours are blocked, resulting in the sky appearing even redder. Ironically, it is the pollution particles in the air that causes some of the most spectacular sunsets.  

What Causes The Sky To Turn Pink? 

Although it may appear to be an unusual and unusual colour for the sky, pink skies are extremely prevalent in large cities, particularly those with high levels of pollution.

During a high-pressure system, when plenty of particles from the pollution adds to the molecules in the air, an effective filter for the scattering of violet light is created.

Although blue light is more visible than violet light under normal circumstances, these unique atmospheric circumstances cause more violet to be scattered more than blue light, resulting in a pink (violet) sky.  

A sunset’s colour can appear pink under similar conditions that create a red sky. Under some circumstances, red light reaching you, combined with red light reflected off particles high in the air, and some scattered blue light making it through, creates a beautiful violet sunset.   

Why Do The Sky Turn Grey?

It is a well-known fact that the sky looks grey when it is overcast and completely covered with clouds. The appearance of the grey colour has a relatively simple explanation.

Clouds are mostly made up of tiny water droplets. Water droplets refract light uniformly, unlike molecules and particles that disperse light according to different wavelengths on a clear day. As a result, the light that passes through the clouds is white. 

The only reason the light appears grey is because the clouds stop some of the light from going through. The varying shades of grey you see in clouds are due to their density, which dictates how much light gets through.

What Causes a Rainbow to Form? 

Rainbows are created when light scatters inside water droplets. This is why rainbows only appear after rain, when there is water in the sky and the Sun is shining. Sunlight enters a rain droplet and bends or refracts as it passes through it. As the sunlight departs the droplet, shorter wavelengths bend more than longer wavelengths, causing the sunlight to divide into the entire spectrum of visible light. The rainbow that results is visible from top to bottom, with the longest wavelengths (red) at the top and the shortest wavelengths (violet) at the bottom.

Sunrises and sunsets

The sun may create brilliant vistas of pink, crimson, and orange in the sky as it rises and sets. The crimson and orange light catches the clouds, creating some of nature’s most breathtaking images. Because of the quality of light, photographers all over the world choose sunrise and sunset. 

When the sun is directly overhead during the day, its light travels directly through the atmosphere to reach us. The sun is near to the horizon at sunrise and dusk. Its light must travel a significantly greater distance through the atmosphere than it does during the day. Almost all of the blue light is dispersed away during this journey through the atmosphere, leaving only the longer wavelengths of red and orange light to travel.

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