Waking up to snow is a pleasant surprise for everyone as we do not even realize when the blanket of white has set and winter has arrived. This has made a lot of people wonder why snow makes everything silent just as softly as it falls. The question arises – is snow a soundproof material or does snow just absorb sound?
You may also have other questions such as why snow makes everything quiet, but when you step on it, there is a distinct sound. If it can make a place different, then why is it so weak against the light? We have compiled this article to explain this phenomenon.
Read on to know more.
Read: Does Wood Absorb or Reflect Sound?
Does Fresh Snow Absorb Sound?
Snow has sound-absorbing properties, but only a particular size and shape can trap the sound. For snow to be able to absorb sound, it needs to be fresh, fluffy fallen snow so that the tiny crystal particles and needles are light and frozen enough to have gaps and are not solid enough to reflect it completely as ice does.
Fresh snow can absorb sound very efficiently. That’s why everything goes very quiet when it starts to snow. A study has even shown that only 2 inches of snow are enough in order to absorb around 60% of sound waves.
However, it needs to be in its fresh fluffy form to be able to absorb sound. If the snow gets too hard, it will reflect the sound rather than absorb it. Also, as the snow melts away, you will also notice that in its liquid form, it loses the ability to obstruct sound waves when they land.
Why Does Snow Absorb Sound?
Snowflakes are not a single particle in themselves but a group of iced crystals that are stuck together. Since there are a number of spaces between these crystals, sound passes easily through the structure and is easily absorbed by them. When these snowflakes group together on the ground and layer on top of each other, it can eventually reduce sound.
Sound absorption is calculated in the ranges from 0 to 1 and the absorption level of snow ranges from 0.5 to 0.9, which means that it can easily suck up most of the sound made around it. The level of absorption can also change as time passes or the amount of snow increases or decreases.
How Much Sound Wave Can Snow Absorb?
The highest range of sound on its absorption scale is 1 and the lowest is 0. On this scale, snow can go from 0.5 and 0.9. This means that depending on the thickness, it can absorb sound from up to 50% to 90% and even those surrounding it. A study by the University of Kentucky College of Engineering states that snow is a strong absorber of sound.
When melted, this power of absorption can reduce drastically as the flakes are no longer close together. In this liquid form of snow, water can absorb sound to a certain extent, but it has a range of 0.569, which is far lesser compared to that of snow. Hence, you can hear everything during rainfall, but the world goes quiet after snow.
Why Does Stepping On Snow Make a Sound?
Stepping on freshly fallen snow can cause a crunching noise by your footsteps. This is because snow is not just frozen water particles stuck together but also bits of dust and debris that freeze with the low temperature. They are also the reason snow can appear in its six-sided dendrite form, tiny needles, crystals, or overall haphazardly. These solid materials, close together in a blanket of snow make the stepping sound you know.
The snowflakes can also group together to form hard pellets, also known as graupels, which are thick enough to be the best state of snow to make snowballs. Since they can be hard and are dense, stepping on them will make them crumble and hence create that sound.
However, not all dry snow that we step on makes a noise. This is because freshly fallen snow is fluffy and the little dendrite and crystals are not as stuck together in a blanket of snow. It needs to be outside for some time before it can make the crunch/squeezes sound.
This is similar to what happens if you leave a bucket full of ice cubes in the fridge – it automatically becomes a big structure of ice. Snow left outside for the time will melt and then quickly attach to form a stronger bond.
Freshly fallen, soft snow will hence disperse to absorb the sound of your footsteps, but overnight snow that has been outside for a long time will create a louder noise when stepped on.
Read: Does Styrofoam Absorb Water?
Why Does It Get Quiet When It Snows?
After it has snowed, the surroundings usually get very quiet. This is because snow does not allow sound to pass through very well. Since the ice crystals and needles are stuck together, they allow sound to not pass through easily. Even if the waves do travel, it must be difficult to get through the gaps which are not visible to humans. These tiny gaps and the structure of snow make them good absorbers of sound.
It has the ability to absorb noises from people, cars, and traffic, and only light, newly fallen snow that is soft to touch can best trap noises. The gaps in between the crystals and needles make the snow porous, which can absorb sound waves better and create a quiet effect. This will still not be done by just some dusting of snow. You would need quite a few inches to have that eerie, quiet weather.
Snow loses its insulating properties when it melts because the snowflakes change shape and the distance between the crystals gets smaller. In the winter, as temperatures change, freshly fallen snow may partially melt before freezing. After the snow changes to ice, it can even amplify neighboring sounds because ice reflects sound waves instead of absorbing them.
Hence, the temporary silence can be replaced by the very snow that caused it once it melts. More reason for people to enjoy rare snow days.
Does Snow Absorb Light?
Snow absorbs sound, but it reflects light so well that it makes it bounce back. When a beam of light hits snow, it goes through all the tiny ice crystals and the gaps between them to bounce around and then hit some of them to get pushed out. Hence, it does not really absorb light but reflects, transmits, and scatters it regardless of its origin, color, or wavelength.
This is also the reason snow may appear white or bluish. Being a very good reflector of light, and being out in the open, snow gets a lot of reflections of colors from its surroundings, and since the same amount of colors that goes in, gets dispersed out, the color of it turns into white. It has also been termed the most reflective surface on Earth.
This is not the case with ice, which usually appears blue as a mass. Light goes much deeper into ice than it does into the snow. Ice is also solid water, which makes it very compact, and does not have the gaps that scatter light.
Longer wavelengths, which are closer to the red end of the spectrum, scatter out more as light travels deeper. Eventually, only blue colors are left to be reflected back to us after the reds have dissipated. As a result, the ice acquires a gorgeous, ominous blue hue.
Read: Does Cork Absorb Water?
Does Snow Absorb Heat?
Snow melts away when exposed to heat. Even if you cannot start a fire, you can easily find other ways and sources of heat that can melt the cold away. However, which one of the two is the stronger element mainly depends on the amount there is. Hence, snow that has covered an area of space can absorb heat from the ground and blanket it in order to stay frozen for a long time.
To understand how this happens, we will look at the case of the Arctic where snow and other iced surfaces are in abundance. The cover of snow throughout regions of the Arctic is great in quantity, and it does two jobs – insulating the ground in winter and reflecting away the sun’s heat, keeping the temperature cool. Since it reflects the heat, it reduces the amount of energy, hence it reduces the temperature as well.
A dramatic drop of up to 10 centigrades in surface air temperature is correlated with the beginning of snow cover in the Arctic in the autumn. The reflecting quality of the snow is responsible for at least half of this quick temperature drop.
This grand cover of snow is, however, still easy to break in and overcome depending on the temperature. Throughout winter, Arctic snow does not have any other substance to dominate over its vast expanse, but once spring starts settling in and the first snow gives away to melting, the cover collapses as the dark ground absorbs the sun’s energy faster and melts away the ice.
Recently, there has been a significant effect of less snow covering the entire Arctic in an acceleration of warming, especially in spring. The shorter length of Arctic snow cover observed between 1970 and 2000 is thought to have boosted warming effects equal to around 5% of the annual warming brought on by human-induced carbon dioxide emissions.
Hence, it is important to understand that while nature is strong enough to have snow absorb heat, Global Warming is real and needs to be taken seriously.
Snow may fall gently but once it has the world under its blanket, it has the power to quieten footsteps and the sound of harsh absorbed car horns, giving us a break from reality. We hope that this article has helped you understand how snow affects the whole environment around us and why it silences the world for a bit.