why does the sky change colors at sunset

There are several wonders of nature but that one that had me curious for a while is why does the sky change colors at sunset?

I have never been much of a nature person but that became different when I fell in love with sunsets. 

The burst of colors right before bejeweled darkness.

It is breathtaking but I know you are not here to gush over the marvelous beauty of sunsets but rather about the reasons behind it.

The two main reasons why the sky change colors at sunset are diffusion and scattering. Some people call it Rayleigh scattering.

Colors Of Sunsets

sunset colors

There are causes of different colors at sunsets that are the same for all the colors of sunset.

But now and then, other environmental factors determine what color is experienced at sunset and why. 

So you see, sunsets are not just beauties of nature, they also tell stories with their colors, stories of the atmosphere.

Pink Sunset

Pink sunset is one of my favorites for several reasons and it does tend to spark curiosity because pink is not part of the 7 basic colors. 

Since pink is not an independent color but rather a mixture of red and white, why is it a color at sunset?

As beautiful and mysterious as it may seem, the reason behind it is quite normal.

Note: Scientists believe that pink is merely a shade of red which makes it a possible wavelength.
pink sky sunset

Purple Or Violet Sunset

This sunset has an even more dramatic story behind it. As some of us might know, the atmosphere has a lot of aerosols.

Aerosols come to be for a lot of reasons like volcanic eruptions, forest fires, or sandstorms. 

When it reaches the stratosphere, it scatters the blue lights and produces a purple-like color.

When the sun goes lower, the sky is filled with violet with a tinge of purple and yellow.

Tip: Aerosols are mixtures of fine solid particles or liquid droplets suspended in a gaseous medium.

Yellow Sunset

During sunset and sunrise, lights tend to travel over a maximum distance, which is why colors with shorter wavelengths, like blue, are not seen. 

The dramatic meaning of the yellow sunset is that it shows mostly after a storm or hurricane.

yellow colored sunset

Orange Sunset

The same concept that applies to yellow sunset applies to orange sunset.

Both colors are not only prominent at sunsets or sunrises but also in the daytime, especially in the afternoon.

Red Sunset

The main concept behind the red sunset is something I think we all know at this point.

Diffusion of light and Rayleigh scattering, which I am sure we discussed already. 

Tip: Because of how easy these concepts are, we almost always get a red sunset.

So far, we have only been talking about sunsets that are red but we all know that is not the only shade of color present in the sky during sunset. 

We know what causes colors in sunsets but why is the sunset different colors, and what do those different colors mean?

Let’s find out more.

Why Does The Sky Change Colors At Sunset?

why the sky changes color

The sky is like a canvas of varying colors of blue, white, red, yellow, orange, and basically all the colors of the rainbow in different shades. 

The color of the sky varies based on the time of day it is. 

During the day, the sky is breathtakingly blue. At night, black with other shades of colors and stars dusted across it. 

And the moments in between i.e., sunset and sunrise, the sky would be a lovely shade of red, yellow, orange, and so much more. 

So why does the sky change even if the color of the sun is the same?

Note: The reason behind this change of colors is mainly in the way sunlight is scattered across the sky. 

Reason #1: Diffused Light

I am going to let you in on a little secret that isn’t necessarily a secret.

The sun always appears yellow or sometimes orange to those who look at it. 

diffused light

But it actually consists of all the basic colors, which happen to be the color a rainbow has.

Every one of those colors tallies with the emission of certain wavelengths. 

Each of those wavelengths has varying lengths, the shortest being blue, and one with the longest length being red.

All those wavelengths of different colors all come into play when light coming from the sun is hit by different particles in the sky. 

After the light has been hit by those particles, the direction of the wavelength changes. 

You know, when you are not facing the sun or looking directly at it, we can still see light that travels through different mediums to ultimately meet our eye. 

It is precisely the same scattered and reflected light that decides the color of the sky.

In the atmosphere, light is scattered all the more, the smaller its wavelength. Because of this, blue light is dispersed more often than red light.

Sunlight Rays Determine Everything 

When the sun is high, the path of the sunlight through the atmosphere is quite short.

Mainly blue is scattered so that the sky appears blue to us during the daytime. 

rays of sunlight

In the early hours of the morning or late in the evening, the sun goes down or is low because it is about to come up.

When this happens, the path of light through the sky is much longer. 

As a result of the scattering, the shorter wavelengths stand a lesser chance and the longer wavelengths gain the upper hand. 

Therefore, the cloudless sky is blue when the sun is up and the pathway of light is shorter and red at sunrise (morning red) and sunset (afterglow) when the pathway of light is longer.

So all this is trying to say is that since blue light has the shortest wavelength, it is seen more often and disappears quickly when the sun disappears. 

The color red, on the other hand, has the longest wavelength.

And it shows best when the sun is about to disappear or reappear hence the color at sunset and sunrise.

Reason #2: Rayleigh Scattering

Visible light is just a section of the electromagnetic spectrum from the violet wavelength through all the colors of the rainbow to red. 

rayleigh scattering sunset

This is at a distance of 750 nanometers. The yellowish-white sunlight is composed of all these colors.

But why then does the cloudless sky appear blue during the daytime and red at sunset? This discoloration of sunlight happens in the Earth’s atmosphere. 

The atmosphere is a mixture of gasses consisting mainly of nitrogen (78 percent) and oxygen (21 percent) molecules. 

Because these tiny particles are much smaller than the wavelength of visible sunlight, they scatter radiation in all possible directions.

Tip: The shorter the wavelength, the stronger.

When Does This Occur?

This physical process is called Rayleigh scattering. 

Rayleigh scattering occurs whenever radiation is scattered by particles much smaller than the wavelength of the radiation. 

rayleigh scattering sky light

This is the case with the gas molecules in the sky. 

The water droplets or ice crystals in clouds, unlike gas molecules, are far larger than the wavelength of light.

There is no Rayleigh scattering here, rather all wavelengths of sunlight are reflected, so that clouds appear white to us.

The cloudless sky appears blue because scattered blue light reaches us from all directions. 

The situation is different at sunset: the air column through which we see the sun is much longer than during the day when it is higher in the atmosphere. 

On the long way through the sky, the blue part of the sunlight, in particular, is scattered out, and the afterglow remains.

FAQ

sunset color faqs

Why Does The Color Of Sunset Vary Everyday?

The dispersion and scattering of lights create the various colors of the sunset by external factors like particles in the air. 

Since the world is constantly changing, so is the atmosphere. 

Meaning the atmosphere can’t contain the same amount of particles that affected the colors of the sunset today and the next day as well. 

So the atmosphere can’t have the same type of dust or the same amount of aerosol every day, which is why the colors of the sunset constantly vary.

Which Color Is The Rarest Sunset Color?

It wasn’t discussed earlier but the rarest sunset color is blue. Yes, you heard me right. 

I know it sounds impossible, but every now and then, some blue wavelength makes it over the distance.

That is when you have a blue undertone in your sunset.

blue sky sunset

Conclusion

So, in summary, why does the sky change colors at sunset? The cloudless sky appears blue during the day, but orange to red in the morning or evening. 

The secret behind this color duo lies in the way sunlight is scattered in the atmosphere.

It is a beautiful occurrence if I’m being honest and if we all want to continue seeing nature’s beauty, avoid pollution.

I hope this article has been helpful. Thank you very much for your time and patience. Stay safe!

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