Read our privacy policy. But what about red sky in the middle of the day — what does that indicate? The answer is high levels of particles in the sky coming from forest fire smoke. Videos showing this phenomenon in Sumatra, Indonesia, set Twitter alight on 21 September. The bright red haze more closely resembled Mars, than Earth. A daytime red sky is very unusual, but smoke pollution in this part of the world is not. The smoke comes from fires illegally set to clear forest areas for plantations.
In Indonesia, this so-called slash-and-burn farming is notorious for being poorly controlled. Peat fires are particularly problematic because they smoulder, which is an incomplete — and very polluting — form of combustion.
The last time fires in this region were this bad — — the resulting air pollution was estimated to have caused over , premature deaths. Neighbouring Malaysia and Singapore also suffer with reduced air quality during large Indonesian forest fires. Spikes in acute respiratory illnesses in the region have been reported. Besides making the sky look blue, it is also the reason why the Sun looks yellow during the day even though sunlight is white.
When the Sun is high in the sky, the light has to travel a shorter distance through the atmosphere. This means most of the yellow, orange, and red light passes through while a small amount of blue and purple light is scattered and removed from the mix. The Sun, therefore, looks yellow for us here on Earth. Due to Rayleigh scattering, most of the light of shorter wavelengths — the blue, violet, and green — are scattered away multiple times, leaving only lights of longer wavelength — the red, orange, and yellow — to pass straight through to the observer.
This is why a rising and setting Sun tends to take on spectacular hues of red, orange, and yellow. 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. Also, storms wash a lot of the big particles out of the air.
Yes, true sunset occurs a minute or so before you see the sun disappear. What you see is a kind of mirage; the light is getting bent around the horizon by the effect of refraction.
Our eyes are sensitive to a very tiny part of the spectrum of the sun's wavelengths, and that's responsible for the way we see our environment. Other creatures seem able to see the ultraviolet area of the spectrum. We can only see a tiny part of what's going on. So a butterfly or a reindeer , which can perceive ultraviolet light, might be seeing a different, perhaps more colorful sunset than we do? The more you look at things, the more you realize how unique your own experience is as a human on this planet, at this particular place and time.
All rights reserved. In simple terms, what makes a good sunset happen? Do dust and air pollution make sunsets more dramatic? Do the seasons affect sunsets? So conversely, could local weather forecasters predict a pretty sunset? Why are sunsets sometimes more dramatic after a major storm? Is it true that by the time we see a sunset, the sun is actually already gone? Sounds like there's a lot of science to sunsets, but it's also a very subjective experience.
This interview has been edited and condensed. 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.
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