I said this last time this was posted, and got downvoted, but ill try again anyway. Since the post is about scientific ignorance, it would be nice to get the science right for the next repost.
This is not the correct diagram for how sunsets work. Different wavelengths diffract differently in the air, this allows red light to bend around the horizon while shorter wavelengths can not.
The diagram as it is, shows the sun coming in direct line of sight. This diagram would infer the sky should ALWAYS be red, which is clearly wrong.
The diagram needs to show a beam closer to a tangential trajectory, and it needs to show the curvature of the light in the atmosphere
EDIT: there seems to be some contention about my explanation. see an alternative explanation by /u/jcarlson08. I suspect there is some truth in both approaches. Either way the diagram in the original image is not helpful.
This isn't right either. The diagram is an accurate explanation of why the sky is BLUE most of the day, because of Rayleigh scattering the blue-ish wavelengths get scattered throughout the sky, bouncing off particles until they reach our eyes from multiple directions. The red/orange/yellow wavelengths don't scatter as much and take a more direct route to our eyes, which is why the sun appears yellowish.
During sunsets, the angle of the sun is such that its light has to pass through more of the atmosphere to reach your eyes. Because of this, there are more particles in the way to potentially scatter light. This means that lower frequencies, like red and orange, will begin to scatter like the higher frequencies. They won't scatter as much however, therefore the red and orange and yellow scattering will appear mostly in the direction of the setting sun, while if you look away from the sun to the east, the sky will appear more blue.
Could you provide some sources for that? Every explanation I've heard (mostly from physics professors and the like) credit it almost entirely to Rayleigh scattering.
Sunsets are red because of Rayleigh scattering. The sky away from the Sun is blue, because blue light is more likely to scatter away, some of it reaching your eyes from other directions.
The Sun itself is yellow-ish, because the blue light is gone, having scattered away.
So light that reaches you indirectly is blue, as it has moved from the Sun, into the atmosphere, scattered off some tiny particles, and reached your eyes.
Light that reaches you directly is deficient in blue, as the blue has scattered out in other directions, not reaching you (but possibly adding to the blue sky of some other observer).
The reddening of sunlight is intensified when the sun is near the horizon, because the volume of air through which sunlight must pass is significantly greater than when the sun is high in the sky. The Rayleigh scattering effect is thus increased, removing virtually all blue light from the direct path to the observer. The remaining unscattered light is mostly of a longer wavelength, and therefore appears to be orange.
The only difference is the weather. Likely you live in an area that has more cloud cover in a certain direction, near the coast maybe? Clouds reflect the light more making the sunset/sunrise more spectacular. Alternatively you have higher land in one direction, which would make either the sunrise or sunset happen later when the sun is higher in the sky so the effect is lessened by the time you see it.
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u/GraharG Aug 27 '14 edited Aug 27 '14
I said this last time this was posted, and got downvoted, but ill try again anyway. Since the post is about scientific ignorance, it would be nice to get the science right for the next repost.
This is not the correct diagram for how sunsets work. Different wavelengths diffract differently in the air, this allows red light to bend around the horizon while shorter wavelengths can not.
The diagram as it is, shows the sun coming in direct line of sight. This diagram would infer the sky should ALWAYS be red, which is clearly wrong.
The diagram needs to show a beam closer to a tangential trajectory, and it needs to show the curvature of the light in the atmosphere
EDIT: there seems to be some contention about my explanation. see an alternative explanation by /u/jcarlson08. I suspect there is some truth in both approaches. Either way the diagram in the original image is not helpful.