Okay, so let's talk about the typical Earthling's perspective. Why do we see more orange and red colors in the sky during sunrise and sunset than we do at other times of day? When a beam of sunlight strikes a molecule in the atmosphere, what's called "scattering" occurs, sending some of the light's wavelengths off in different directions.
This happens millions of times before that beam gets to your eyeball at sunset. The two main molecules in air, oxygen and nitrogen, are very small compared to the wavelengths of the incoming sunlight—about a thousand times smaller.
That means that they preferentially scatter the shortest wavelengths, which are the blues and purples. Basically, that's why the daytime sky is blue. The daytime sky would actually look purple to humans were it not for the fact that the sensitivity of our eyes peaks in the middle [green] part of the spectrum—that is, closer to blue than to purple.
But at sunset, the light takes a much longer path through the atmosphere to your eye than it did at noon, when the sun was right overhead. And that is enough to make a big difference as far as our human eyes are concerned. It means that much of the blue has scattered out long before the light reaches us. The blues could be somewhere over the West Coast, leaving a disproportionate amount of oranges and reds as that beam of light hits the East Coast. So the same ray of sunlight is hitting people in both the Rockies and the Appalachians?
Basically, the East gets the West's leftovers at sunset? Yes, I think a lot of people don't realize that. Everything is connected. And as humans, we like to think color is concrete: "Oh, that's a blue sky," or "That's a brown table. Absolutes don't really exist in color perception. It's rather disquieting when really you start thinking about it! No, you often hear that, but—assuming you mean typical pollution in the lower atmosphere—it's a myth.
It's actually the opposite: Large particles in the lower atmosphere tend to mute and muddy the colors because they absorb more light and scatter all the wavelengths more or less equally, so you don't get that dramatic filtering effect. In areas with a lot of haze, you don't typically see the types of sunsets that are likely to appear on a wall calendar— or in, say, National Geographic.
You see bright ones in the fall and winter particularly, especially in the East, because the air along the path of the ray of sunlight tends to be dryer and cleaner. I grew up in Baltimore, and this is part of why I got interested in weather. I would wonder: Why is the sunset so pretty tonight? And there weren't answers to questions like this in standard weather books, because it's more about physics than forecasting. Speaking of forecasting, what about the saying: "Red sky at night, sailor's delight; red sky in morning, sailors take warning.
Those spectrally pure colors are telling you there's a sizable swath of clear air off to your west that's likely to be over you the next day. Yeah, you can forecast them to a certain degree. I guess it's a question of who cares—maybe filmmakers or photographers would find that information useful, but most people just want to know if it's going to rain or not. There's often a slanting band of clouds on the back side of the departing weather system, and that can act as a sort of projection screen for the low-sun colors, better than a horizontal band would.
The slant means it captures more of the orange and red light, and if the cloud is thin enough, it will reflect those colors down to you. Severe Weather U. Radar U. RADAR by state. Satellite U. Great Plains Satellite - C.
Great Plains Satellite - S. As we sight at various objects in our surroundings, the color that we perceive is dependent upon the color s of light that are reflected or transmitted by those objects to our eyes. So if we consider a green leaf on a tree, the atoms of the chlorophyll molecules in the leaf are absorbing most of the frequencies of visible light except for green and reflecting the green light to our eyes.
The leaf thus appears green. And as we view the black asphalt street, the atoms of the asphalt are absorbing all the frequencies of visible light and no light is reflected to our eyes. The asphalt street thus appears black the absence of color. In this manner, the interaction of sunlight with matter contributes to the color appearance of our surrounding world. In this part of Lesson 2, we will focus on the interaction of sunlight with atmospheric particles to produce blue skies and red sunsets.
We will attempt to answer these two questions:. The interaction of sunlight with matter can result in one of three wave behaviors: absorption, transmission, and reflection. The atmosphere is a gaseous sea that contains a variety of types of particles; the two most common types of matter present in the atmosphere are gaseous nitrogen and oxygen. These particles are most effective in scattering the higher frequency and shorter wavelength portions of the visible light spectrum. This scattering process involves the absorption of a light wave by an atom followed by reemission of a light wave in a variety of directions.
The amount of multidirectional scattering that occurs is dependent upon the frequency of the light. In fact, it varies according to f 4.
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