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Trivia

The sun is yellow, the snow is white, and the sky is blue.
If snow reflects all light, how does it get white when the sun is yellowish?
Douglas Krantz -- Fire Alarm Engineering Technician, Electronic Designer, Electronic Technician, Writer






Why is Snow White?

By Douglas Krantz

Question: If the sun is yellow, why is snow white?
Answer: Because the Sky is Blue.


Um, the riddle seems to be nonsense, but really, it does hold a scientific truth.

The light from the bluish white sun has the blue removed and scattered in the atmosphere, making the sunlight appear yellowish.
As the light from the sun travels through the atmosphere, the blue value light is scattered by the moisture. This gives us the yellowish light from the sun we see.

White Snow - Yellow Sun

The snow, indeed, does look to be white. Whereas the real sun doesn't look as yellow as these drawings show, it does have a definite yellow tinge to it, especially when compared to real snow.

Sunlight Above the Atmosphere

Above the atmosphere, the sunlight starts out with a blueish white color. As the light from the sun pierces the atmosphere, it is modified; some of the blue light from the sun is diverted so it no longer comes down to the earth in a straight line.

Blue Sky

Moisture in the atmosphere scatters the blue light, and re-scatters the blue light again and again
Yellow sunlight and blue sky light is combined by the snow to make white snow.
The snow takes all this light, the yellowish light from the sun and the bluish light from the sky, and recombines it to make white light.
so it seems to come from all directions of the sky. Some of the blue light from the sun is scattered back into space, a little is absorbed by the atmosphere, and in what we observe as blue sky, much of it does get to earth.

What's left of the original white light from the sun is white, minus some of the blue component. To us it looks yellowish.

Size Ratios

The sun is very intense, but it's also a very small portion of the sky.

On the other hand, the blue of the sky isn't all that intense. However, to make up for the lack of intensity, it takes up most of the sky. Added together, all that blue light from all over the sky equals a lot of blue.
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This means that as a whole, when added together, the light from the yellow sun and the light from the blue sky provides a total of white light.

The Snow Combines the Light

Snow, of course, is what adds the light together. The light is reflected and refracted by the snow, which makes the snow a combiner of the white light we see.





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Douglas Krantz

Describing How It Works
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Electrical Flow


On this website, most references to electrical flow are to the movement of electrons.

Here, electron movement is generally used because it is the electrons that are actually moving. To explain the effects of magnetic forces, the movement of electrons is best.

Conventional current flow, positive charges that appear to be moving in the circuit, will be specified when it is used. The positive electrical forces are not actually moving -- as the electrons are coming and going on an atom, the electrical forces are just loosing or gaining strength. The forces appear to be moving from one atom to the next, but the percieved movement is actually just a result of electron movement. This perceived movement is traveling at a consistent speed, usually around two-thirds the speed of light. To explain the effects of electrostatic forces, the movement of positive charges (conventional current) is best.

See the explanation on which way electricity flows at www.douglaskrantz.com/
ElecElectricalFlow.html
.