Walking in the snow feels nice. The air is cold, the ground is white, and the snow makes a fun sound when you step on it. While scientists understand many aspects of snow, such as its color and how snowflakes form, the mystery of why it squeaks when stepped on remains unsolved.
(Photo : Unsplash/Annie Spratt)
Understanding the Intricacies of Snow Formation and Its Audible Effects
Understanding why snow squeaks underfoot involves delving into the intricate process of snow formation. For snow to precipitate, the atmosphere must contain moisture, and temperatures need to be at or below freezing, typically around 32°F (0°C). As water droplets freeze onto tiny particles like dust or pollen, snowflakes gradually take shape.
According to the National Snow and Ice Data Center, snow adheres to the ground when the temperature remains at least 41°F (5°C), preventing immediate melting.
Once a sufficient layer of snow blankets the ground, each step produces a distinctive squeak. Professor W. Craig Carter from the Massachusetts Institute of Technology (MIT) likens this phenomenon to running a fingertip across the teeth of a comb.
He explains that the characteristic sound arises from the simultaneous fracturing of numerous minute structures, akin to the breaking of countless tiny snow crystals.
The delicate architecture of snowflakes is pivotal in generating this audible effect. Upon contact, snowflakes undergo a process known as sintering, wherein icy connections termed "necks" form between crystals, resembling beads on a necklace. Professor Carter elucidates that stepping on snow disrupts these connections, leading to the familiar crunching sound.
In essence, the squeak arises from the breaking of these icy bonds between snow particles, producing a symphony of sounds with each footstep across the snowy landscape.
Temperature Also Causes the Show Squeak Underfoot
Carter suggests that temperature affects snow's crunchiness, more noticeable in colder climates where freezing water creates a dry, crisp texture. Warmer temperatures yield denser snow with less audible effects. Ski wax formulas adjust to temperature variations.
In temperatures below 14 degrees Fahrenheit, footsteps fail to melt the snow, causing ice crystals to rub together and produce a distinctive squeak. Additionally, near-freezing temperatures coat ice crystals with a liquid-like layer, reducing friction and minimizing sound.
Furthermore, colder temperatures increase the likelihood of crunching as sintering occurs. Carter notes a similar phenomenon with wet sand, where grains adhere due to slight solubility in water, generating analogous squeaking sounds.
The snow's surface temperature, regulated by the ambient air temperature, determines its crunchiness, with colder air resulting in colder surface layers. A deeper snowpack near the ground remains warmer due to proximity to the earth's heat, insulated by snow's insulating properties, slowing heat transfer from the ground to the chilly air above.
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