Sunrise vs sunset

[TreeofLifeStairs]

I could be wrong, but my observation is that sunrises look more yellow where as sunsets look more red. Have you found this to be the case too? If that is the case, my question is why? Isn’t it physically the same process just in reverse?

 

[Jeff15]

Isn’t it physically the same process just in reverse?

Yes, I would have thought so....

 

[TreeofLifeStairs]

@Vieri posted a pic of the Tuscan sunrise that shows how yellow it is.

 

[photoflyer]

I am not sure but this photo does both at the same time. I took it in Helsinki on January 30th 2017 at high noon. I often show it to people who have never experienced the high latitudes in mid-winter and ask them to determine if it is a sunset or sunrise.

 

[AlanKlein]

I don't know if they are or aren't. I try to avoid getting up that early.

But if they are, it could have to do with other things going on. For example, it's usually calmer in the morning. Wind picks up more as the day goes on. Another factor could be the dew point. Since it's cooler overnight before sunrise compared to an afternnon sunset, the relative humidity and water vapor in the air can be quite different. That could effect light waves and color. Also, because there's more human activity during the day, the pollution and other smog and vehicle and industry exhausts that goes into the air will effect the colors. In the morning, everyone is sleeping and the air cleared up over night.

 

[jeffW]

Also, because there's more human activity during the day, the pollution and other smog and vehicle and industry exhausts that goes into the air will effect the colors.

this and the amount of dust that has been kicked up due to the warmer day temps

 

[waday]

Here's a good article about it: Do Sunrises Look Different from Sunsets?

 

[smoke665]

It's my understanding that the color is basically the same with reds being predominate. Particles in the air scatter the light through the day and night, but because of the angle of the sun the light travels farther through the atmosphere at sunrise and sunset. What Determines Sky's Colors At Sunrise And Sunset?

 

[TreeofLifeStairs]

It's my understanding that the color is basically the same with reds being predominate. Particles in the air scatter the light through the day and night, but because of the angle of the sun the light travels farther through the atmosphere at sunrise and sunset. What Determines Sky's Colors At Sunrise And Sunset?

Right, I’m familiar with scattering. That gives reason for why the sky changes color as the sun rises and sets but doesn’t answer why (or if) a sunrise looks different from a sunset. The pollution may be a good answer but how about places with very little pollution? In those areas the sunsets should look very golden like the sunrises. I remember trips to Kauai (I don’t know for certain that there’s less pollution there but presumably there’s less) and the same yellow/golden sunrises and orange/red sunsets occurred like I see all the time here in the Bay Area.

I’m going back to Kauai this September; I’ll have to see if I can get some pictures of both and post them and see if people can tell if it’s a sunset or sunrise.

 

[smoke665]

The pollution may be a good answer but how about places with very little pollution?

Pollution doesn't necessary cover the gamut of possibilities in the atmosphere. In one of my favorite hangouts (Smokies), they get their name from the “volatile organic compounds" (VOC) in the air, produced by the forest. Depending on the makeup of the VOC's it can either block or scatter certain wavelengths. In the case of the Smokies the trees that are most common in the region have high concentrations of VOCs that scatter blue light. Also, the Smokies get a lot of rainfall and sunlight, experience high levels of humidity, and have a lot of stagnant air. Again as the angle of the sun changes that light takes on different hues, as it travels further through the atmosphere. Burning coal for example produces sulfate particles that actually block light.

 

[Derrel]

In my region, we have many miles to the Cascade Mountain Range at sunrise, but at sunset the closer Coast Range and even-closer Tualatin Mountain range cause the setting sun to be blocked off by close mountains (Coast Range) or extremely close mountains (Tualatins), so the sun rays do not travel through much atmosphere at sunset time, and also there can often be quite a bit of marine layer clouds/rain over the Pacific Ocean. At sunrise however, the sun's rays crest the Cascade Range some many miles to the east,and come through clear, mostly un-polluted mountain-zone atmosphere. So...in my particular region, Oregon's Willamette Valley, we have a very distant eastern mountain range, and a relatively close set of western mountains. Sunrise and sunsets here are very different.

If one drives to the Oregon Coast, it's possible to watch a sunset that comes through nothing but a tiny bit of ocean breeze-borne air; this is hugely different than watching a sunrise where the sun peeks over Mount Hood many miles to the east, and the light slants through populated areas, with agricultural particulates, or forest fire smoke in the fire season, etc.. Last summer we had terrible forest fires east of Portland, and the sun at sunrise was a brilliant fiery RED BALL for weeks on end.

 

[smoke665]

Last summer we had terrible forest fires east of Portland, and the sun at sunrise was a brilliant fiery RED BALL for weeks on end.

Interesting trivia side note, part of the color has to do with the wavelength of the light. The blues and greens are shorter wavelengths making them more easily scattered, the longer wavelengths such as red and yellow light are least affected by scattering. When the sun is at the horizon (sunrise, sunset) the red is intensified because the light being received directly from it must pass through a greater proportion of the atmosphere nearer the earth's surface, where it is denser or holds more pollution/particles/etc. which removes a significantly greater proportion of the shorter wavelength (blue) and medium wavelength (green) light from your view. The remaining unscattered light is mostly of longer wavelengths and appears redder.

Even though I know why it does it, I'm always blown away by how red the sun will appear when viewed through the smoke from a large fire.

 

[markjwyatt]

"Bloody red sun of Phantastic L.A.", Jim Morrison, Peace Frog on Morrison Hotel (~1970, when smog was near peak in LA)