Why is the sky blue in summer and sometimes clear gray in winter ?
539871
in the summer the sky is blue because the atmosphere dullens the color of outer space but in the winter the sky is the color it is because of the water particles that are in the sky
680880
We see the blue sky because of Rayleigh scattering.  Short wavelengths (blue light) are scattered more than long wavelengths (red light).\n\nAs the sun dips below the horizon, it doesn't get dark immediately.  We still see some light, this is twilight.  At night, even though sunlight is scattered, it doesn't scatter all the way around the globe.  Hence you eventually observe a black sky.
24151
Everyone else is wrong. This has nothing to do with water. The sky is blue because as the light waves pass trhough the air they collide with molecules, effectively scattering the blue wavelenghts of light. This is demonstated by the fact that the sky at lower angles appears more blue, because there is more air that the light must travel through.
117362
One meaning to this is that you did not check the archive of previously asked questions before you posted your question about the sky's color. This has been asked and answered almost 400 times so far here (see link below). \n\nHowever, the reason the sky appears blue (at least most of the daylight hours) is that the atmosphere is mostly oxygen and nitrogen, which are just the right size molecules to scatter the blue light, but let the other colors pass unimpeded. \n\nSo when you take the blue away from the mostly white sunlight, you get sorta yellow sunlight. \n\nAs the sun sets, the sunlight passes through more air, and more blue is scattered away, leaving the sunlight even less blue, that is, more orange. \n\nAs the sun sets even farther, even more blue is scattered away, and the sunlight appears red.
522607
no the sky is no actually blue, have you noticed that at night you can see space? well thats because during the day the sun ray that come through our hemisphere are hitting against the massive amount of Ocean on our Earth, they do not reflect, but instead refract off the water molecules and transmit into the air, shooting all the way back up to our hemisphere, this gives us the sight of a blue sky.
617565
The water particles,mixed in the air ( sky ), are responsible for this.The sunlight is refracted by those water molecules and thus we see the colour of the sky as blue.As you may remember,in the rainbow colours,Blue comes just after Violet and Indigo which are not that prominent as Blue. \nThus we see the sky blue.
917666
Why is the sky blue?\n\nhttp://math.ucr.edu/home/baez/physics/General/BlueSky/blue_sky.html\n\nhttp://www.sciencemadesimple.com/sky_blue.html\n\nGood luck.\n\nKevin, Liverpool, England.
1113645
A clear cloudless day-time sky is blue because molecules in the air scatter blue light from the sun more than they scatter red light.  When we look towards the sun at sunset, we see red and orange colours because the blue light has been scattered out and away from the line of sight.\n\n\nBecause the universe is not infinitely old, that puts a limit to how long the\nlight from all those stars can have travelled. So some of the light has not\ngotten here yet. Because stars do die out, that means that their light dies\nout too - which means that we may get the light from some stars at one time,\nand the light from some other stars at a different time, but not all the \nlight\nof all the stars that everywhere put together. Finally, because the \nuniverse is\nexpanding, the light gets weaker before it gets to us. All in all, this means\nthat there is not enough light from all those stars to make any point in \nspace\nbright.
749637
Because the sky is kinda blue that time....\n\nAlso, because of the gloominess that flows all around in the night time....
92915
The sky appears blue due to the scattering of sunlight by dust particles in the air.\n\nSunlight is comprised of light in different wavelengths and can easily be split with a prism.  The dust particles in the air are of the right size that they scatter blue light preferentially.  As a result, we see the sky blue.\n\nThe sky is black at night simply because there isn't any blue light to be scattered.\n\nIncidentally, moonlight is yellow because that is the generally reflected colour off the moon's surface.  It is reflected light strongly in the yellow waveband. The yellow light is not affected by atmospheric scattering.
680108
There are two reasons. Both are caused by a property of light -- it is made up of different wavelengths.\n\n(1) When light passes through our atmosphere, it diffracts & blue wavelength gets scattered towards earth. This is why the sky is blue. When viewed from the beach, the sea is also blue because it reflects the sky, of course.\n\n(2) Another reason is not by diffraction, rather, light under the sea is blue because water absorbs longer wavelength of light through distances over about 20 metres.
1015359
using simple physics\n\nThe blue color of the sky is due to Rayleigh scattering. As light moves through the atmosphere, most of the longer wavelengths pass straight through. Little of the red, orange and yellow light is affected by the air.\n\nthe grass is green because the other colors are absorbed and only green is reflected. Grass and most other plants are green because they contain a pigment known as chlorophyll.\n\nSun isn't really yellow. The color yellow is a purely human interpretation of a collection of radiation that hits the retinae of our eyes and gets processed by our visual cortex.
213070
Ocean's colour seems to be blue because it gets the sky's reflection over it.\nAnd the colour of the sky is blue bcuz of the various gases present in the atmosphere\nMainly nitogen and oxygen.
274364
the sky appears blue becuase that is the color of ozone (O3), the gas that surrounds the earth.
163899
essentially it is the same reason the sky is blue - rayleigh scattering inside the ice itself.  see the page below for details:\nhttp://www.gi.alaska.edu/ScienceForum/ASF7/773.html
31576
The Earth's sky is blue because the air molecules (largely nitrogen\nand oxygen) are much smaller than the wavelength of light. When light\nencounters particles much smaller than its wavelength, the scattered\nintensity is inversely proportional to the 4'th power of the\nwavelength. This is called "Rayleigh scattering," and it means that\nhalf the wavelength is scattered with 2**4 = 16 times more intensity.\nThat's why the sky appears blue: the blue light is scattered some 16\ntimes more strongly than the red light. Rayleigh scattering is also\nthe reason why the setting Sun appears red: the blue light has been\nscattered away from the direct sunlight.\n\nThus, if the atmosphere of another planet is composed of a transparent\ngas or gases whose molecules are much smaller than the wavelength of\nlight, we would, in general, also expect the sky on that planet to\nhave a blue color.\n\nIf you want another color of the sky, you need bigger particles in the\nair. You need something bigger than molecules in the air---dust.\n\nDust particles can be many times larger than air molecules but still\nsmall enough to not fall out to the ground. If the dust particles are\nmuch larger than the wavelength of light, the scattered light will be\nneutral in color (i.e., white or gray)---this also happens in clouds\nhere on Earth, which consist of water droplets. If the dust particles\nare of approximately the same size as the wavelength of light, the\nsituation gets complex, and all sorts of interesting scattering\nphenomena may happen. This happens here on Earth from time to time,\nparticularly in desert areas, where the sky may appear white, brown,\nor some other color. Dust is also responsible for the pinkish sky on\nMars, as seen in the photographs returned from the Viking landers.\n\nIf the atmosphere contains lots of dust, the direct light from the Sun\nor Moon may occasionally get some quite unusual color. Sometimes,\ngreen and blue moons have been reported. These phenomena are quite\nrare though---they happen only "once in a blue moon...." :) The dust\nresponsible for these unusual color phenomena is most often volcanic\nin origin. When El Chicon erupted in 1982, this caused unusually\nstrongly colored sunsets in equatorial areas for more than one year.\nThe much bigger volcanic explosion at Krakatoa, some 110 years ago,\ncaused green and blue moons worldwide for a few years.\n\nOne possible exception to the above discussion is if the clouds on the\nplanet are composed of a strongly colored chemical. This might occur\non Jupiter, where the clouds are thought to contain sulfur, phosphorus,\nand/or various organic chemicals.\n\nIt's also worth pointing out that the light of the planet's primary is\nquite insignificant. Our eyes are highly adaptable to the dominating\nillumination and perceive it as "white," within a quite wide range of\npossible colors. During daytime, we perceive the light from the Sun\n(6000 K) as white, and at night we perceive the light from our\nincandescent lamps (2800 K, like a late, cool M star) as white. Only\nif we put these two lights side-by-side, at comparable intensities,\nwill we perceive a clear color difference.\n\nIf the Sun was a hot star (say of spectral type B), it's likely we\nstill would perceive its light as "white" and the sky's color as blue
244426
The blue sky phenomenon is caused by Rayleigh scattering of sunlight through the atmosphere.  The scattering is strongly polarized at 90 degrees from the direction of the sun.  The light is polarized tangentially with respect to the sun.