The dynamic way different-shaped snowflakes perform distinct 'dances' within clouds has been found to hugely influence how much precipitation forms and is likely to fall to Earth. The discovery of this unique cloud choreography has the potential to guide more accurate forecasting of weather events, especially rainfall and snow.
University of Reading researchers modeled Mother Nature with artificial snowflakes and applied physics analyses to predict how and when a diverse group of ice crystals would melt into raindrops and fall as precipitation. They created various shaped 3D-printed snowflakes that replicate those found in nature, and then let them fall through a water-glycerine compound to mimic atmospheric conditions. They captured their descent through the tank with high-speed cameras, then mapped their charted their movements as they 'fell.'
They found that the snowflakes performed four different kinds of 'dances,' or movements, as they fell: Stable (straight, vertical fall), zigzag (a sort of side-to-side motion), transitional (zigzagging and spinning) and spiraling (spinning or rotating).
"Watching snow gently falling can be mesmerizing, so it has been a joy to uncover the ways in which different ice crystal shapes pirouette and zigzag on their downwards journey," said lead researcher Jennifer Stout.
The scientists found that, to their surprise, the intricately shaped dendrites – like those pictured above – had a stable, straight-line-down 'dance,' but left turbulence in their wake, yet others such as hexagonal ice crystals were quick to become unstable and have greater sideways movement.
Essentially, the more eccentric the 'dance' – such as zigzagging or spiraling – the more chance the snowflake has of bumping into another ice crystal. The more crystals that collide, the larger the mass becomes, in turn creating a higher chance of rain (or snow).
In addition to this, the type of dance the ice crystals performed, impacted how much Sun was absorbed or reflected by the clouds, affecting their form and lifespan.
"Understanding the dance of a snowflake is not only beautiful but can help us understand the reflectivity of clouds," said Stout. "Each snow crystal in a cloud acts like a tiny mirror, reflecting and refracting the light that passes through it."
"By predicting the choreography of an entire cloud, we could better improve our understanding of the atmosphere and the processes which lead to rain and snow," she added. "This intricate coordination of snowflakes can also create a big visual impact, causing stunning phenomena such as sun dogs and ice halos."
Ultimately, looking into the intricate choreography of the tiny ice formations within clouds could help satellite data, and in turn meteorologists, more accurately predict the likelihood of rainfall and its severity.
The researchers also noted that their modeling has broader long-term climate implications, with the potential to better understand the properties of cloud reflectivity and how they absorb atmospheric heat.
The study was published in the journal Atmospheric Chemistry and Physics.
Source: University of Reading via Phys.org
