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244 views

What is the most likely cause for this strange lighting at sunset?

Yesterday's sunset was a little bit weird in several countries (Saudi Arabia, Egypt, Kuwait). Here's a video & picture, in case it wasn't clear enough it felt as if everything was being lit by a ...
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1answer
59 views

Why sky is blue? [closed]

The major factor of different scattering is the ratio of wavelength to the size of particles which are working as microscopic scattering mirrors. In a sparse particle medium like air, the longer the ...
1
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1answer
34 views

Formation of Red and blue bands in the sky

Today at the time of sunset I saw this The sky is divided into two parts one In red and one in blue which are very distinctive Can anyone tell how? The upper part of the image points towards the ...
1
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1answer
66 views

quantum mechanical treatment of rayleigh scatterring

Is there a quantum mechanical explanation of light scattering by atmospheric gases? Classically, treating the atmospheric particles as excited dipole antennas, we know that the amount of scattering is ...
4
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1answer
70 views

Does sky luminance really decrease in steps as the Sun goes deeper under the horizon?

Playing with some atmospheric scattering simulations, I've come across a fact that, as the Sun goes lower under the horizon, sky luminance (neglecting sources of light other than the Sun) appears to ...
2
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3answers
83 views

Is there a difference between the red sky in the morning and in the evening?

It certainly has a different feeling to it, but does the temperature or earth's rotation or the clouds or anything else really make it two different physical phenomena or at least different colors? ...
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1answer
45 views

If the Sun had a larger surface temperature how would that affect its appearance to us in the sky?

I thought about this when I came across wiens displacement law which says the higher the temperature, the lower the peak wavelength. If the sun was a lot hotter, and its peak wavelength wasn't in the ...
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1answer
20 views

Light in atmosphere versus space

The atmosphere appears bright because of scattering of light whereas space appears dark due no atmosphere to aid scattering. Is it possible to demonstrate it with such darkness in a huge vaccum ...
3
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1answer
75 views

While flying over Rome we noticed that during sunset, there was a green color between the red and blue of the sunset sky. What causes it?

The picture has only been trimmed and not edited. The green is visible when the red or orange tapers off into the blue. Is this different from what causes the green flash? We were flying from Rome.
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3answers
218 views

How does scattering of light happen in atmosphere?

I know that the scattering of light decreases as inversely proportional to the 4th power of wavelength. But what happens at the atomic level? Does the photon get absorbed and re-emitted? Does the ...
0
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0answers
19 views

How does brightness affect color? [duplicate]

How does brightness affect the color of light? For instance, the sun might be yellow because of the blue scattering when the light travels through the atmosphere - but if you look at it, it seems ...
0
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2answers
112 views

Why does the sun always have some whiteness? [duplicate]

So the atmosphere scatters light on its way to earth, making the color of our sky. For example, when the sky is blue on a clear, sunny day, the sunlight appears somewhat yellow because the blue light ...
2
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1answer
93 views

Why are distant mountains grey?

I have read this question: Where in the atmosphere is the blue light scattered? where John Rennie says: For the same reason, distant mountains keep their color. Also, the distant mountains don't ...
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2answers
82 views

Why does purple appear in a rainbow?

It is said that people and digital cameras have color sense only for red, green and blue. So when we see violet/purple in a rainbow, whether with our eyes or in a photo, we should be seeing a color ...
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2answers
84 views

Simple computation of the spectrum of the blue sky

Given an approximation of the spectrum of extraterrestrial sunlight by blackboby radiation at 5800K, between 360 and 800nm, is there a simple formula or algorithm that can be used to make an ...
0
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1answer
104 views

What type of mirage is this?

I am very new to the world of mirages and would like some information as to the type of mirage in this picture which I took this morning. It is the cargo ship African Kalmia which passed my location ...
31
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1answer
3k views

Does more light from Andromeda get scattered in the atmosphere than in the entire trip to Earth?

Fires have been burning here in Northern California. Today there was just a slight haze of smoke. The sun had a slight red hue to it. As expected the lower it got the redder it became. The blue light ...
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1answer
44 views

Why do our eyes perceive changes in apparent position of stars as twinkling?

Okay, so we all know that the changes in refractive index leads to continuous changes in star's apparent position but then why don't we see them moving up and down rather than brighten and dim in ...
13
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2answers
319 views

Only sea water appears blue in color, why this is not happening in river water?

Is the salt in the water the reason for scattering sunlight into blue?
1
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1answer
94 views

Some Rayleigh Scattering questions

Last week I've heard about Rayleigh scattering for the first time, when the classic 'why is the sky blue?' question has crossed my mind and I must admit that it is fascinating! However, I do have a ...
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2answers
56 views

what is the refraction index in the upper atmosphere(e.g Theromosphere)?

I've been searching for the refraction index in the upper atmosphere such as Stratosphere and Thermosphere but I can't find it, all that I've seen is all equation without any number that I can use it. ...
2
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1answer
189 views

Can Rayleigh scattering explain the orange color of the Titan sky?

It is my understanding that Rayleigh scattering depends on both the length of the particle as well as the wavelength. Due to the similar lengths of molecular nitrogen and oxygen it is blue light that ...
0
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0answers
226 views

What are the average wavelengths and brightnesses of sunlight across the stages of twilight?

I understand that before sunrise, twilight shows several colors, so I'm looking for the average color (wavelength) and brightness (lux) of light that is being projected from the sky before the sun ...
4
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2answers
233 views

Sodium sometimes absorbs orange-yellow light, sometimes emits it? Huh?

Usually, we are told that sodium emits orangish-yellowish light, which is why city streetlamps are that color. Now, I read in New Scientist magazine that exoplanet WASP-96b is bluish because the ...
3
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2answers
1k views

Why is this cloud blue?

I saw these clouds on the horizon, behind a ridge (apologies I couldn't get more pixels): Why is the front cloud darker than the cloud behind? There were no other clouds that I saw which could've ...
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1answer
80 views

How to mathematically work out the color of the sky? [duplicate]

I was wondering if there is a way to mathematically work out the color of the sky, using the laws of geometric/wave optics.
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3answers
991 views

Why do we feel the sunlight the second the sun gets out of the clouds?

The earth is 149.600.000 km away from the sun and the speed of light is 299 792.458 kilometres / second, therefore, it would take sunlight, on average, 8 minutes and 20 seconds to reach earth. Now, ...
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3answers
1k views

Why isn't the Sun blue?

If I believe right, blue flames are hotter than red ones and if I recall correctly it's because blue tend to ultraviolet. Then why is the sun, which's capable of warming whole planets, red instead of ...
9
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3answers
302 views

Why do rainbows always appear to be far away from us?

We know that the single rainbow we see is actually a continuous cone of rainbow. If so, why don't we see that cone instead of a single, far-away rainbow?
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1answer
23 views

Are the blue/red colors of scattering visible only Because of the large size of the atmosphere?

hypothetically, would you be able to see the scatter of color if you shine a light on $N_2$/$O_2$ particles in a small model of the atmosphere? is it possible on an entirely shrunken scale or is there ...
5
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1answer
1k views

Why is the sky blue and the sun yellow?

The blue color of light of the sky is due to Rayleigh scattering. But the sun itself appears yellow in color whereas the scattered sunlight itself appears blue. Why does this happen? Should the sun ...
3
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1answer
196 views

Does the brightness of day follow simple harmonic 'motion'?

Is it really true that the brightness during the day on earth follows simple harmonic motion? My teacher mentioned this as an example but it doesn't feel obvious to me by any stretch of the ...
2
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1answer
1k views

Why does the sun/moon appear red when there are fires?

Recently, in the United States, the moon and sun have become very deep red when they are near the horizon. The reason given for this is that there have been extensive wild fires in the Northwest. So, ...
0
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1answer
183 views

Does a beam of light change direction when it leaves the atmosphere?

Imagine a laser beam shining straight up from the surface of the earth. As the light gains altitude it encounters less and less air and soon no air at all. My question is when it leaves the refractive ...
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0answers
25 views

Saturation-like effect of the atmosphere on sunlight?

Does the atmosphere have any kind of saturation effect whereby the intensity of the light hitting the surface of the earth is non-linearly proportional to the output of the sun? In other words, is ...
5
votes
3answers
207 views

Why are nearby clouds so different in brightness?

I was traveling in the day time from Saint-Petersburg to Sochi and was watching various clouds passing by. After some time I noticed that even though some clouds are very close to each other, they ...
3
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1answer
464 views

Why is there a large dip in the spectral distribution of sunlight at 760 nm?

I'm doing research with the spectral distribution of sunlight and I noticed that there was a large dip in wavelength at 760 nm. I was wondering if anyone knew why that was! My thoughts were that there ...
3
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2answers
905 views

How to see wind?

Is there a wavelength of light at which you could see air moving? I was thinking it would be amazing to put on a pair of goggles which enables you to see how air moves around across a landscape, while ...
11
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3answers
376 views

Why aren’t sunsets red when viewed from low earth orbit?

So “Why are sunsets red?” seems to be a pretty common question and it has to do with Rayleigh scattering in the atmosphere. I’m following some game dev tutorials (example implementation) on how to ...
0
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2answers
194 views

Why don't we get VIBGYOR instead of white light?

Why doesn't the atmosphere disperse white light from the Sun like a prism as air is a dispersive medium? If it really did so, shouldn't we be receving the 7 colours separately instead of one?
8
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1answer
3k views

Can a rainbow be seen from above

I saw this picture of a "rainbow from above" Based on what I understand about rainbows, some googling and my experience chasing them, if I saw one and try to fly above it, the phenomenon will ...
0
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2answers
494 views

What determines the pattern, size and distance in a rainbow?

On the top picture why is the second rainbows colors reversed? I have observed a rainbows that was huge from behind the horizon that began vertically and the small ones made with a sprayer hose. I ...
13
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2answers
1k views

What causes a circle of light to appear opposite the sun when looking from an airplane?

Today I saw a circle of light outside my plane window on the clouds, as if someone was shining a bright, tightly focused flashlight, or perhaps like the halo that sometimes appears around the sun. I ...
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1answer
42 views

Merging solar light signals

In the image below, there is a curve-shaped conduit which transmits solar light. The light is collected at different spots and injected into the conduit at various spots with fiber optics. As per ...
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1answer
238 views

Paradox about the arrival of light from the Sun to our Earth

I recently watched a documentary which said that the sun is 8 light minutes away from the earth. I know that at the rise of the sun we actually see it a few minutes ago, say 2 minutes before it is ...
1
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1answer
313 views

How much air would be needed to block sunlight?

Was watching a sunset on the sea, I was wondering what would be a lower bound for the thickness of air needed to almost completely obscure the reddish light of the sun, or at least to make it ...
2
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3answers
1k views

Can aurorae/northern lights be used as an energy source?

Their temperature is high, they have high velocity. Can they be used as an source of energy? If not why? If yes how?
1
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1answer
2k views

Why are light-bulbs filled with low pressure gas?

When incandescent light bulbs are manufactured, they are filled with an inert gas to insulate the filament and prevent its sublimation. The pressure inside a freshly manufactured light bulb is ...
1
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0answers
52 views

Why is the sky never green?But it can be slightly blue-green? [duplicate]

The colour of the sky is determined by light scattered from the sun reaching the earth from a new direction. The shorter the wavelength the greater the light is scattered. On a dull day, with the sun ...
2
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1answer
121 views

Why do clouds appear pinkish after rain?

Monsoon winds are blowing over India and after every rain I observe that the clouds are turning pinkish, even during the night. What causes such a phenomena? Or are the observations coincidence?