Ice and snow are both frozen states of water. But while ice is transparent, snow is absolutely white. Why is this? Read on.
Much of the fascination about snow is because of its milky white color. The sense of beauty and purity exuded by the snow layered terrains is mesmerizing. The term ‘snowhite’ is used to describe incomparable whiteness. Most people love the snow for the way it looks –white and serene.
Isn’t it interesting to note that the ice in your refrigerator is transparent while snow is white, although both ice and snow are solid states of water? Snow is just a bunch of ice crystals stuck together. So where does it get its distinctive color from?
Visible light or white light is made up of many different colors of light. Different objects have different colors because they absorb some colors and reflect others. Our eyes receive the reflected colors and the object appears to be of that particular color. Such objects are called opaque.
Why is ice transparent?
Transparent objects allow most of the light falling on them to pass through. Very little of the light that falls on them is absorbed. Some objects change the direction of the rays of light that fall on them. Such objects are called translucent. The ice in your fridge is not transparent but is actually translucent. This means that it does not allow the light to pass through a straight path. So light exits from a block of ice in a different direction than it enters it, thus making the ice appear translucent.
What is snow?
Snowflakes are formed when water vapor in the air suddenly freezes without first converting into liquid. The air currents keep on tossing these crystals in the atmosphere. This makes them collect into groups and float down to earth as snowflakes. Snow is therefore a whole bunch of individual ice crystals arranged together. On close observation it has been seen that snow is a six-rayed ice crystal of delicate quality.
What makes it white?
When a ray of light enters a layer of snow, it goes through an ice crystal on the top, which changes its direction slightly and sends it on to a new ice crystal, which does the same thing. Basically, all the crystals bounce the light all around so that it comes right back out of the snow pile. The same thing happens to all the different colors of the light rays that fall on it, so all colors of light are bounced back out. These colors combined in equal measure give us white, so this is the color we see in snow. In short, we can say that it is the reflection of light from the surfaces of the ice crystals that make the snow look white.
Did you know?
The sun is powerless to melt clean snow.
We have seen how snow reflects the light that falls on it. In fact, newly formed snow reflects about 90 per cent of the sunlight that falls upon it. This is the reason sun cannot melt clean snow. When snow does melt, it is not because of the sunlight but because of the warm air around, usually from the sea.
Interestingly enough, after snow becomes ice, the sun is still not very effective in melting it. Now a different problem arises because of the transparency of ice to light. The sunlight passes through it very quickly. It does not stay in the layers of ice long enough to get absorbed and thus raise the temperature of the ice and melt it. So when the ice is very cold and the layers very thick, the whole summer passes before any melting occurs. This is what happens in the Antarctic region.
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