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17 April 2014 12:48 pm ,
Vol. 344 ,
Using the two high-quality genomes that exist for Neandertals and Denisovans, researchers find clues to gene activity...
A new report from the Intergovernmental Panel on Climate Change (IPCC) concludes that humanity has done little to slow...
Astronomers have discovered an Earth-sized planet in the habitable zone of a red dwarf—a star cooler than the sun—500...
Three years ago, Jennifer Francis of Rutgers University proposed that a warming Arctic was altering the behavior of the...
Officials last week revealed that the U.S. contribution to ITER could cost $3.9 billion by 2034—roughly four times the...
An experimental hepatitis B drug that looked safe in animal trials tragically killed five of 15 patients in 1993. Now,...
- 17 April 2014 12:48 pm , Vol. 344 , #6181
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ScienceShot: The Sharp Shape of Frozen Water
12 October 2012 3:04 pm
Frozen water droplets take on a whole new shape when they freeze: Instead of staying round, they form a pointy tip, and eventually sprout a tiny forest of ice crystals on their surface. In order to observe these effects, researchers dripped tiny beads of water on a plate kept at a chilly -20°C. In the 18 seconds that it took the 4-millimeter-diameter droplets (top row) to solidify, researchers snapped photos of the water freezing from the bottom up. During the final stage of freezing, the ice drops developed a pointy tip (middle row), which continued to grow and eventually formed delicate ice crystals on the surface, the team reported last month in Physics of Fluids. Researchers believe the unusual pointy tip is caused by the vertical expansion of the ice combined with the surface tension on remaining liquid. Once frozen, the sharp tip of the drop attracts water vapor from the air, and produces treelike ice crystals (bottom row).
See more ScienceShots.