In winter, snow falls from the sky. The snow covers the ground, making it completely white. However, if you think about it, snow is actually frozen water. Water and ice are transparent, so why does snow appear white?
To understand this question, we need to understand the properties of light, the structure of ice, and the shape of snow crystals. Here, we will explain in detail from a scientific perspective why snow appears white
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What is snow anyway?
Snow is a collection of ice crystals formed when water vapor in the air freezes
Snow is created in clouds through the following process:
1. Water vapor cools and turns into ice crystals.
2. The crystals grow and take on a hexagonal shape.
3. The crystals stick together to form snowflakes.
4. They become heavy and fall to the ground.
The snow crystals that form at this point basically have a symmetrical hexagonal structure, which is due to the bonding structure of water molecules
Each snowflake is made of transparent ice, which means that it is essentially a transparent substance
So why does snow look white when it gathers together?
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The Basics of Light - How Do We See Colors?
First, let's understand how we see color
Sunlight appears white at first glance, but it is actually a mixture of light of various colors
This is
light with different wavelengths, such as red, orange, yellow, green, blue, indigo, and violet
This phenomenon is called dispersion of light, and when light passes through a prism it splits into the colors of the rainbow
The color of an object is determined by three factors:
1. Absorbing light
2. Reflecting light
3. Scattering light
For example:
• Leaves → Reflect green
• Charcoal → Mostly absorbs (black)
• Paper → Reflects a lot of light (white)
In other words, an object that appears white
is one that reflects all colors of light equally.
Snow also fits this criteria
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The main reason why snow looks white is because of light scattering
The reason snow appears white
is because of light scattering.
When light hits snow, it bounces off the ice crystals in the snow in all directions
This phenomenon
is called light scattering
Here's what happens inside the snow:
Sunlight
↓
hits a snow crystal
↓
reflects
↓
hits another crystal
↓
reflects again
↓
hits another crystal
that light bounces off the snow
As a result
, all colors of light are reflected equally
, and our eyes see it as white.
This is how it works
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Why is snow white even though ice is transparent?
This is the most mysterious point
The ice is clear.
The water is clear.
But snow is white
The reason is
The presence of air
Snow is not just ice
Ice + Air
is
The structure of the snow is actually quite loose
It is said that
more than 90% of its volume
The presence of air between ice crystals causes:
• Ice → Refraction
• Air → Refraction
• Boundary → Reflection
is repeated
At this point, it is important
Refraction
and
reflection
.
Light changes direction at the boundary between different materials
In the snow
Ice ↔ Air
Ice ↔ Air
Ice ↔ Air
There are thousands of such boundaries
This causes light to scatter in a complex way
This is why snow appears white
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Why fresh snow looks especially white
Freshly fallen snow looks especially white
This is because the crystals have a beautiful shape
Characteristics of fresh snow
: • Crystals are not broken
• Contains a lot of air
• Has a fine surface
This results in strong light scattering
In other words
The more scattering there is, the whiter it appears
That is what it means
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When snow loses its whiteness
In fact, snow isn't always pure white
The color changes depending on the conditions
① Melted snow
When snow melts, it becomes water
The water is clear so
the whiteness disappears.
This is because there is less air in the snow
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②Compressed snow
Snow at ski resorts is compressed
Less air causes
less light scattering and
makes the surface appear slightly grayer.
There are times when this happens
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③Dirty snow
The snow on the roads turns black
This is
• soil
• exhaust fumes
• garbage
This is because they absorb light
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Why snow sometimes looks blue
When a lot of snow accumulates, it can appear blue
For example
, glaciers
, snow caves
, and deep snow
And so on
this is
Rayleigh scattering
is involved.
Inside the ice
: Red light is more easily absorbed
Blue light is more easily scattered
Therefore, it may appear bluish
The same principle is why glaciers appear blue
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- Snowflake Shape
Snowflakes actually come in countless shapes
This varies with temperature and humidity
A Japanese physicist named
Ukichiro Nakaya is famous for his research on snow
He is famous for his work on artificial snow
"Snow is a letter sent from heaven"
He left behind the following words
Research has shown that
: • Plate-like crystals
• Needle-like crystals
• Dendrites
I found that there are many different forms
But in any case, basically
Light-scattering structure
It appears white because it has
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Why snow is so dazzling
Being outside on a snowy day can be very dazzling
This is snow
Very high reflectivity
To have
The reflectivity of snow is
80〜90％
It is said that..
This means it reflects most of the sunlight
Therefore, in the snowy mountains
Snow blindness
(keratitis caused by ultraviolet rays)
This can sometimes happen
This is why you need sunglasses when skiing or mountain climbing
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summary
The reasons why snow looks white can be summarized as follows:
1. Snow is a collection of ice crystals.
2. There is a large amount of air between the crystals.
3. Light is reflected multiple times at the boundary between the ice and air.
4. Light is scattered in all directions.
5. All colors of light are reflected equally.
As a result, in our eyes
Snow looks white
That's why
In other words, the whiteness of snow
A natural phenomenon caused by light scattering
We can say that
The transparent ice gathers together, mixes with the air, and scatters the sunlight, creating the beautiful snowy scenery
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