Pink Clouds: Pollution's Surprising Sky Art?

Red, orange and pink clouds are caused by the scattering of sunlight by the atmosphere. This phenomenon occurs almost entirely at sunrise and sunset. The presence of pollutants in the atmosphere can cause clouds to appear yellow, and this is sometimes seen in urban areas with high air pollution levels. However, excess pollution can also dampen the overall sunset experience.

Red, orange and pink clouds are caused by the scattering of sunlight by the atmosphere

The size of the smoke particles is just right for filtering out other colours, meaning that red, pink and orange colours can be seen more vividly in the sky. The particles are higher in the atmosphere than the pollution which hangs over cities. As the sun sinks closer to the horizon, its rays are no longer filtering through the pollution layer, but shooting upwards into the sky, where they are reflected off any clouds.

If the sky is filled with aerosolised smoke particles, they turn the light a deep red before it hits the clouds, and the result is ragged layers of scarlet and gold over a deep indigo strip. Particles of any kind, even much smaller than the wavelength of visible light, will make the sky brighter but at the expense of its purity of colour. Although aerosols may make a sunset red, excess pollution will also dampen the overall sunset experience.

The size of smoke particles can filter out other colours, making pink clouds more visible

The colour of clouds can be influenced by the presence of pollutants in the atmosphere. Red, orange and pink clouds are usually the result of the scattering of sunlight by the atmosphere at sunrise and sunset. However, the presence of certain particles in the atmosphere can also cause clouds to appear pink.

The effect of smoke particles on the colour of clouds is also influenced by their position in the atmosphere. Smoke particles that are higher in the atmosphere than the pollution over cities are more likely to cause vivid sunsets. This is because, as the sun sets, its rays are no longer filtering through the pollution layer but are instead shooting upwards into the sky, where they are reflected off any clouds.

The presence of pollutants in the atmosphere can also cause clouds to appear yellow. Clouds with a yellowish tint are caused by the presence of nitrogen dioxide and are sometimes seen in urban areas with high levels of air pollution.

Pollution can dampen the sunset experience

While pollution can cause beautiful sunsets, it can also dampen the sunset experience.

Red, orange and pink clouds occur almost entirely at sunrise and sunset and are the result of the scattering of sunlight by the atmosphere. The size of smoke particles released by fires is just right for filtering out other colours, meaning that red, pink and orange colours can be seen more vividly in the sky. However, particles of any kind will make the sky brighter but at the expense of its purity of colour.

Yellowish clouds caused by the presence of nitrogen dioxide are sometimes seen in urban areas with high air pollution levels. If the sky is filled with aerosolised smoke particles, they turn the light a deep red before it hits the clouds, resulting in ragged layers of scarlet and gold over a deep indigo strip.

The effect is more pronounced when there is a high concentration of large aerosols. While aerosols may make a sunset red, excess pollution will also dampen the overall sunset experience.

The presence of nitrogen dioxide can cause yellowish clouds

While pink clouds are not directly caused by pollution, the presence of pollutants in the atmosphere can contribute to the vivid colours of sunsets. The size of smoke particles released by fires can filter out other colours, allowing red, pink and orange to be seen more vividly.

Yellowish clouds, on the other hand, can be caused by the presence of nitrogen dioxide, a reddish-brown gas with a pungent, acrid odour. Nitrogen dioxide is formed when nitric acid reacts with water, and it is commonly seen in urban areas with high levels of air pollution. The gas can cause skin and eye irritation, bronchitis, and even death.

The yellow colour of clouds is due to the presence of pollutants in the smoke. In urban areas with high levels of air pollution, yellowish clouds can be observed due to the presence of nitrogen dioxide. This gas is formed when nitric acid reacts with water, and it can have serious health impacts, including skin and eye irritation, bronchitis, and even death.

Nitrogen dioxide is not the only pollutant that can cause yellowish clouds. Fine dust particles a few micrometers across can also give clouds a yellow hue. These dust particles can be present in urban areas with high levels of air pollution, contributing to the overall yellowish appearance of the clouds.

In addition to yellowish clouds, nitrogen dioxide can also cause brown fumes. These fumes are often seen in agricultural settings, such as silage clamps, and can pose a significant health risk to both people and animals.

The sun's rays reflect off clouds at sunset

However, red, orange and pink clouds are usually the result of the sun's rays reflecting off clouds at sunset. This is because the smoke particles released by fires are small enough to filter out other colours, allowing red, pink and orange to be seen more vividly. These colours are also more vibrant when the particles are higher in the atmosphere, above the pollution that hangs over cities.

The effect of pollution on sunset colours is complex. While particles in the atmosphere can make the sky brighter, excess pollution can dampen the overall sunset experience. This is because particles of any kind, even much smaller than the wavelength of visible light, will make the sky brighter but less pure in colour.

So, while pollution can contribute to the vibrant colours of sunsets, it can also dull them if the concentration of pollutants is too high. The specific conditions, such as the size and concentration of particles, will determine the final colours we see.

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