Why do sunsets and sunrises look so different? Isn’t it technically the same thing?
In: Earth Science
Temp and barometer are both different at night and in the morning which changes how particles respond to air and light. On top of that, one is going up and the other down. I doubt color temp across the spectrum is different between the two but the fact they’re opposite direction has to do something to your eyes. I think one thing that makes a difference is that the sunrise and sunset are actually just an illusion for the first and last 15 minutes respectively. When you see the beginning of the sunrise you’re not actually seeing the sun but a reflection off our atmosphere. Even when the sun pokes over the horizon it’s still not actually the sun. I assume reflecting from two different directions makes a difference in how it looks as well. There’s enough differences between the two that it makes sense they don’t look the same.
The ELI5 version: your eyes see differently depending on whether it’s getting brighter or darker.
Longer version: During the day your eyes are light-adjusted, and you’re primarily seeing the world through color-sensitive cones. As the sun sets and the world gets darker, your eyes don’t shift to night mode as fast as the light level changes. So your eyes remain sensitive to color, with an emphasis on reds, greens, and blues; but it gets perceptibly darker faster, and due to the [Purkinje Shift](https://en.wikipedia.org/wiki/Purkinje_effect), as your eyes adjust to darkness the blues and purples stand out more.
During the night your eyes have had time to get dark-adjusted. You’re primarily seeing the world through mostly monochromatic rods that are 1000x more light sensitive than the cones. You see the sunset coming way ahead of the sun actually cresting the horizon, but because of the Purkinje Effect you see the blues of the sky most prominently. As sunrise approaches your rods pick out subtle changes in light easily, but are largely insensitive to changes in color. Those changes in color happen after the sun crests the horizon as your eyes start to become light adjusted. But at this point the Purkinje Shift is happening in reverse, so as your eyes get light adjusted they pick out the pinks and reds and oranges mostly prominently, and the blues and purples seem muted in comparison to sunset.
Here’s [an article on that exact subject](https://www.livescience.com/34065-sunrise-sunset.html).
The key excerpt is the following:
>All “twilight phenomena” are symmetric on opposite sides of midnight, and occur in reverse order between sunset and sunrise, the authors note in “Color and Light in Nature” (Cambridge University Press, 2001). That means there’s no inherent, natural cause of a major optical difference between them.
In short, in the absence of other factors (increased pollution through the day, etc) there is no real natural difference, but there may be a difference is in the observer’s awareness of the time of day and your body’s physiological response as well. For example, your eyes may be more sensitive in the morning due to being dark adapted, so your perception may be a bit different than it is in the evening.
The one thing that *is* different between sunrise and sunset is the angle at which the sun leaves/approaches the horizon:
>According to the astrophysicist Neil Degrasse Tyson, director of the Hayden Planetarium in New York, there’s also a trick for distinguishing a sunrise from a sunset played in reverse. Because of Earth’s tilt, the sun doesn’t rise or set along a vertical line, but at an angle. “When viewed from all latitudes north of the Tropic of Cancer (23.5 degrees north latitude), the sun always rises at an angle up and to the right, and sets and an angle down and to the right,” Tyson writes on his website. “That’s how you can spot a faked sunrise in a movie: it moves up and to the left. Filmmakers are not typically awake in the morning hours to film an actual sunrise, so they film a sunset instead, and then time-reverse it, thinking nobody will notice.”
I want to add to some of these answers as a gas phase chemist:
The composition of the atmosphere at each level is different in the evening vs. the morning. The sun having been out all day drives a ton of complex chemical reactions in the atmosphere – so by the time the sun sets, there’s an entirely different mixture of chemicals in the air than when it comes up.
That’s not the whole story but it does cause some of the differences.
The difference is in the location. Your sunrise comes from behind the picturesque mountains to the east, while your sunset dips below neighbor Cletus’s run-down work shed.
The color of the sky is from a phenomenon called Rayleigh scattering. The simplest explanation is that the sky color is affected by the angle of the light. The way you can hold a prism in a light beam and make rainbows on the wall or other colors. Gases in our atmosphere do the same thing with light from the sun. Change the angle and you change the color. That is why you have different colors at different times of day and different times of year.
ELI5: temperature changes and differences in dust, moisture, clouds, etcetera change what we see on the ground!
Much more complex explanation: (I’m on mobile sorry for bad typing) sunsets aren’t blue because the water and nitrogen in the air cause Rayleigh scattering so most of the blue light gets filtered out and scattered (also why the sky is blue) but since the sun is low in the sky and therefore a ray of light spends more time in the atmosphere all of the blue light is stripped out. The colors we see in the sky are strictly due to more scattering of what’s left of the other colors and are due to different things like clouds and moisture and dust. Dust suspended in the sky is quite fine, so it’s actually somewhat transparent but only to certain wavelengths. Every element and combinations of elements has a well understood spectrum of what happens when light hits it. It will either absorb and in turn re-emit, reflect, transmit, or scatter. As the different types of dust and therefore a different combination of elements are in the sky as well as different moisture content, pressures, and temperatures (yes pressure and temperature do affect how light behaves) the sunset we see from the ground can be drastically different day to day and it’s also why sunrises and sunsets look different from each other. Source: I’m an optical engineer light do be my jam
DO they look different? I’ve never noticed any difference. What exactly looks different about them?
Keep in mind that one is constantly getting brighter and the other is constantly growing dimmer/softer. It’s subtle but it’s there and is noticeable (hence the reason we watch in the first place). This is in addition to what is mentioned about particles and humidity. That’s also why it’s harder to tell the difference in photos as opposed to experiencing it in real life or seeing it on film.
In addition to what people are saying about the atmosphere, there’s also the movement of the earth. Due to the spin of the earth, you are moving towards the sun in the morning and away from it in the evening. When you move toward the sun, the wavelengths of light are ‘crunched.’ By bringing yourself closer, there’s less time between waves. Similarly light is ‘stretched’ in the evening because you are going away from it. This change in movement effects your interaction with the light and therefore what you see
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