Does Pollution Really Cause Sunsets?

According to an urban legend, pollution is the cause of a bright vibrant sunset.

What Causes a Sunset?

Over the history of man, people have tried to explain the reason why the beauty of sunsets differ from any other time of the day and have come up with many theories. Some people try to link sunsets to mystical beings while others link the event to deities. However, scientists have studied the reason why picturesque sunsets are found in varied locations and the reason why such sunsets occur during particular months. The variations of the hue of sunlight at any time of the day are caused by the interaction of the light with particles in the air. The particles include dust, water molecules, or even smog from cities. Light from the sun is comprised of a spectrum of many colors same as a rainbow which when combined at different wavelengths is viewed as white light as it enters the atmosphere. However, during sunrise and sunset, the light enters the atmosphere at an angle and therefore travels through a “thicker” atmosphere. The light then encounters many particles in the atmosphere and the different colors bounce off the particles at different rates in a process known as scattering. The dispersion of these colors causes the different hues viewed during sunset. This effect is further amplified if the location is in the tropics or desert. In the tropics, the air is humid and is full of water molecules floating around. These water molecules are the barrier on which the sunlight scatters while forming brilliant views during sunsets and sunrises. The effect is minimal during midday due to the less length of atmosphere the light travels through. In the desert areas, due to the presence of sand, the air is usually filled with dust particles on which the sunlight scatters causing the effect.

Pollution and Sunsets

Several cities have experienced spectacular sunsets in recent years, and many scientists attribute this to air pollution. These cities have millions of vehicles that transit through their highways and roads every day and these vehicles emit millions of cubic meters of pollutants into the atmosphere. These pollutants create smog which covers the city’s atmosphere. When the sun rises and sets, the sunlight traveling through the atmosphere comes in contact with these pollutants and scatters creating beautiful sunsets, a case where dirty practices create beauty.

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