Name: Soothing Science: The Light You See at Sunset
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While a sunset may seem like any other ordinary thing, a number of physical elements had to come together, in just the right way, for you to bear witness to this colorful display.

Relax to the sound of the ocean and discover the science behind sunsets.

While a sunset may seem like any other ordinary thing, a number of physical elements had to come together, in just the right way, for you to bear witness to this colorful display.

Soothing Science: The Light You See at Sunset

Relax to the sound of the ocean and discover the science behind sunsets.

Nature

Soothing Science: The Light You See at Sunset Published on April 5, 2023Narrator: Some days as the sun starts to set, the sky lights up with a beautiful display of colors: deep reds, vibrant oranges, intense coral pinks, cotton candy skies—as if it were on fire.The sun emits all the colors of the rainbow. We see that combination as white. So from space, the Sun appears white, but here on Earth, we often see the sun as yellow when it’s high in the sky because of the Earth’s atmosphere.Visible light travels in electromagnetic waves of varying lengths. We see these waves as the colors of the rainbow—violet and blue are the shortest wavelengths we see, red and orange, the longest. These wavelengths measure from 0.0000007 meters to about 0.00000038 meters, but the gas molecules in our atmosphere are even smaller.When light enters the atmosphere, it gets scattered by gas molecules like oxygen and nitrogen in the air. All of the colors are scattered, but because blue wavelengths are the shortest, they’re scattered more.This is the main reason why we see a blue sky as opposed to a green or even yellow sky.So then, why are sunsets shades of red and orange? During a sunset, light from the sun needs to travel further through our atmosphere. That means more blue wavelengths are filtered out, allowing the longer red and orange wavelengths to peer through and give us the vibrant sunsets we’re used to.Everyone in the same latitude is actually seeing the same rays of light, it just appears as different colors as light travels away from the sun and because of atmospheric scattering.Let's say a ray of sunlight is coming towards Earth. As it enters Earth’s atmosphere, oxygen and nitrogen cause the blue wavelengths to scatter to produce a sunny afternoon sky in San Francisco. But the red and orange wavelengths continue to travel through the atmosphere and scatter to produce a stunning sunset in Boston.Contrary to popular belief, dust and pollution are not responsible for more colorful sunsets. If that were true, then cities like New York and Los Angeles would be applauded for their sunsets. Dust and pollution are helpful, to some extent, but most of the sunlight is scattering at mid and upper-levels of the atmosphere.So then, why are some sunsets brighter than others? It turns out temperature has a lot to do with it. Cold air generally contains less water vapor, which clings to particles like dust and pollen, making them swell up and block sunlight.Cold air typically comes from the arctic, where there are fewer trees and industrial activities to produce particles that could also block light. So winter sunsets are more vibrant not only because of less humidity, but also because there are fewer particles in the air.But sunsets look different day-to-day because of the types of clouds in the sky.If it’s cloudy and overcast, you’re not going to see much of a colorful display during sunset from the ground. But let’s say you hop on a plane and fly above the clouds, suddenly you’re greeted by a sea of reds, pinks, and oranges. You’ve just crossed the “boundary layer.” It's the atmospheric layer where we all live and it traps larger particles like dust and pollution.But not all clouds block light coming from a sunset. Some clouds, like the wispy and feathery cirrus clouds, are high enough to reflect the last red-orange rays of a setting sun back to the ground.Weather patterns can also influence a sunset. The contiguous United States is underneath a jet stream, a band of air that flows from west to east in the mid and upper levels of the atmosphere. Weather systems like rain showers or blizzards are disturbances to that jet stream.Where the disturbance starts, on the eastern side, the air cools and expands, over time leading to cloud formations and worsening weather conditions. Meanwhile, on the western side, the air clears and dries. This is what fosters a visually vibrant sunset after a storm. This is the origin of the adage: “red sky at night, sailor’s delight; red sky in the morning, sailor take warning.”While a sunset may seem like any other ordinary thing, know that a plethora of physical elements had to come together, in just the right way, for you to bear witness to this colorful display.

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Soothing Science: The Light You See at Sunset

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