# Tag Info

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At sunset the sunlight that we can see passes through a large (many hundreds of kilometers) distance inside the atmosphere. As it propagates, part of it gets scattered away due to Rayleigh scattering. The smaller wavelengths are scattered more than the larger ones. This means that what remains is redder than what is emitted by the Sun. This makes the solar ...

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Signals have been relayed optically through free space historically. For example the optical telegraph or semaphore system used in 19th C. France. It didn't operate at the speed of light because the time taken to relay a message at each station (reproduce the received signal from one side to a transmitted signal on the other side) is much greater than the ...

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There is a really nice answer by @Ruslan, I would like to add a few things you might find interesting: There is something called afterglow, and this is (in part aside from Rayleigh scattering) responsible for the reddish (pinkish) horizon after sunset. An afterglow is a broad arch of whitish or pinkish sunlight in the sky that is scattered by fine ...

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Aerosol particles (such as dust, SO2, black carbon, etc.) do indeed act as cloud condensation nuclei. However, the wide range of specific characteristics (size, shape etc.) of the different aerosol particles and the diversity of the atmospheric conditions in different locations and seasons, lead to many different and interrelated effects of aerosols upon ...

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I know this has already been answered and accepted, and I agree with the answer by Eubie Drew. However, there are several things in the answer and comments that can be misinterpreted or are misleading. I just wanted to clarify a few things here. The absolute speed of a shock wave is determined by the piston/driver causing it, not the speed of sound, $C_{s}$...

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