Sunsets And Pollution: A Complex Relationship

Sunsets are often yellow, orange, pink, and red, and these colours are caused by the sun's light having to travel through more atmospheric particles to reach us. The shorter blue and green wavelengths scatter more easily, while the longer wavelengths, which produce orange and red colours, make it through, giving us those rich vibrant colours. While sunsets are caused by this phenomenon, known as Raleigh scattering, pollution can deepen the colours when the sun is above the horizon.

Sunsets are caused by Raleigh scattering

The colours of sunsets are affected by particles in the atmosphere, and those could be pollution, but they could also be dust and other naturally occurring phenomena, such as volcanic eruptions. For example, the wildfires in California in 2018 caused more red sunsets in Indiana as the smoke travelled east.

While pollution is not the sole cause of the colours of sunsets, it can deepen the colours when the sun is above the horizon. As one source puts it, "In an atmosphere with no junk at anytime, you'll never get a sunset that would make someone with normal colour vision say, 'Wow that's red!'".

Sunsets are enhanced by pollution

The colours we see at sunset are affected by particles in the atmosphere, and those could be pollution, but they could also be dust and other naturally occurring stuff. For example, volcanic eruptions can lead to really spectacular sunsets.

The added material in the atmosphere gives the light even more to pass through and thus more to react with. This is why sunsets are often yellow, orange, pink, and red. And because red has the longest wavelength of any visible light, the sun is red when it’s on the horizon, where its extremely long path through the atmosphere blocks all other colours. Pollution can deepen the colours when the sun is above the horizon.

In an atmosphere with no junk at all, you'll never get a sunset that would make someone with normal colour vision say, 'Wow that's red!' says Craig Bohren, professor emeritus of meteorology at Pennsylvania State University. "It is certainly true that the 'pollution' results in redder sunsets."

Sunsets are caused by the sun passing through more atmosphere

The colours we see during sunsets are affected by particles in the atmosphere, which could be pollution, but could also be dust or other naturally occurring phenomena, such as volcanic eruptions. While pollution may not be the sole cause of sunsets, it can enhance the colours we see, especially when the sun is above the horizon.

The idea that sunsets are more vibrant in polluted cities is based on the fact that the added material in the atmosphere gives the light more to pass through and react with. However, it's important to note that sunsets have been painted for hundreds of years, pre-dating the industrial revolution and most human-made pollution.

According to Craig Bohren, professor emeritus of meteorology at Pennsylvania State University, "In an atmosphere with no junk at anytime, you'll never get a sunset that would make someone with normal colour vision say, 'Wow that's red!'". He goes on to explain that pollution does indeed result in redder sunsets.

Sunsets are caused by volcanic eruptions

Sunsets are caused by a phenomenon called Raleigh scattering, which occurs when light travels through more atmospheric particles to reach us. During sunset, the shorter blue and green wavelengths scatter more easily, while the longer wavelengths, which produce orange and red colours, make it through, giving us those rich vibrant colours.

Volcanic eruptions can lead to particularly spectacular sunsets. The particles in the atmosphere caused by volcanic eruptions can create a deeper red colour in the sky. This is because volcanic eruptions emit large amounts of aerosols into the atmosphere, which can cause the sky to appear red.

However, it's important to note that sunsets can also be enhanced by other types of pollution, such as smoke from wildfires. The added material in the atmosphere gives the light more to pass through and react with, resulting in deeper colours.

Additionally, the position of the sun in the sky relative to your position on the ground can also affect the colours of a sunset. When the sun is on the horizon, its extremely long path through the atmosphere blocks all other colours except red, as red has the longest wavelength of any visible light.

Sunsets are caused by wildfires

Sunsets are caused by Raleigh scattering, which is when light travels through more atmospheric particles to reach us. Shorter blue and green wavelengths scatter more easily, while longer wavelengths, which produce orange and red colours, make it through. This is enhanced by pollution, but sunsets are not caused by pollution. However, a professor of meteorology has said that pollution does cause redder sunsets.

Wildfires can cause pollution, which in turn can cause redder sunsets. For example, in August 2018, there were more red sunsets than normal in Indiana. This was due to the smoke from the wildfires in California travelling east. The smoke from the wildfires added more material to the atmosphere, which gave the light more to pass through and react with, resulting in redder sunsets.

Volcanic eruptions can also cause redder sunsets in the same way as wildfires. The particles from the eruption are thrown into the atmosphere and scatter the light, causing the vibrant colours we see at sunset.

While pollution can enhance the colours of a sunset, it is not the only factor that contributes to their beauty. The position of the sun in the sky also plays a role, as when the sun is on the horizon, its extremely long path through the atmosphere blocks all other colours except red. This means that even in areas with less pollution, sunsets can still be red.

Additionally, sunsets have been painted for hundreds of years, pre-dating the industrial revolution and most human-made pollution. This suggests that while pollution can enhance sunsets, it is not the only factor that contributes to their beauty. Sunsets are a natural phenomenon that can be enjoyed by people all over the world, regardless of the level of pollution in their area.

Frequently asked questions