SUGGESTION Laura Tanure
ILLUSTRATIONS Aluísio Cervelle Santos
1. Technically called an ice stalactite, or brinicle, this rare underwater phenomenon was first documented in 1974. It only occurs in the polar regions, during the winter. At this time, the temperature above the sea drops to at least -40 oC, much colder than ocean water, around -2°C
two. Under these conditions, the freezing of the surface does not form a solid ice, as in icebergs, but “porous”, with internal channels. Through them, salty and very cold water flows, directed down due to its density and the flow of heat at the bottom of the sea (the “less cold” water rises and the colder sinks)
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3. As it passes through the internal channels, the super-cold water carries more salt, changing the density and becoming colder. When it leaves the “pipe”, the brine jet cools the ocean water around it, which is less dense, less cold and ends up freezing. That is, the barrel is millimetrically extended and the stalactite grows
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4. The sea needs to be calm so as not to break formation. If it manages to reach a certain size, it becomes self-sustaining and grows unbridled, until it reaches the bottom of the sea. On the ground, the process continues as a “river of ice” winds its way across the surface, freezing beings that can’t escape, like starfish
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A brinicle filmed by the BBC channel near Razorback Island, Antarctica, took six hours to reach 10 m in height. Click here to check the video
SOURCES BBC and Discovery websites, and articles Ice Stalactites: Comparison of a Laminar Flow Theory with Experiment, by Seelye Martin, University of Cambridge, and Brinicles as a Case of Inverse Chemical Gardens, by Julyan Cartwright, University of Grenada