THE UNIVERSITY of Reading has announced that analysis of snowflakes could hold the key to improving rain forecasting, in light of new research.
A paper has been published by researchers from the university’s meteorology department examining the physical motion of falling ice crystals which may help meteorologists to better estimate how snowfall translates into rainfall.
This change is a crucial stage in the formation of many types of rain, and scientists say that being able to predict how the reflectivity of snowflakes could improve our understanding of how atmospheric conditions lead to rainfall.
The paper details how a research team used 3D-printed facsimiles of snowflakes of various shapes and sizes, which were dropped through a tank filled with a mixture of water and glycerine.
High-speed cameras recorded how artificial flakes of different sizes and shapes, including simple hexagonal plates to multi-branched flakes, the data from which was used to reconstruct and track trajectories in three dimensions.
The paper explains that the falling patterns are not well understood– ice crystals have complex and irregular shapes which means they can exhibit fluttering, spiralling, and tumbling motions.
Researchers found, however, that simpler shapes became unstable earlier and that more complex shapes retained their stability despite a tendency to create turbulence in their wake.
Scientists say the implications could have significant impact on forecasting, as they wpuld improve the understanding of how radar signals reflect from water and ice particles in the air.
This would lead to an improved understanding and interpretation of the signals we receive from weather radar systems, in turn improving estimations of when atmospheric ice becomes rain.
The paper also posits that this could also improve our understanding of how clouds reflect sunlight and trap heat within the atmosphere, potentially improving climate modelling and more long-term weather forecasting.
The paper, Stable and unstable fall motions of plate-like ice crystal analogues, was published in this month’s edition of the journal of Atmospheric Chemistry and Physics.
Jennifer Stout, who led the research, said: “Watching snow gently falling can be mesmerising, so it has been a joy to uncover the ways in which different ice crystal shapes pirouette and zigzag on their downwards journey.
“Understanding the dance of a snowflake is not only beautiful but can help us understand the reflectivity of clouds–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.
“This intricate coordination of snowflakes can also create a big visual impact, causing stunning phenomena such as sun dogs and ice halos.”
The full research paper is available to read via: acp.copernicus.org/articles/24/11133/2024/
