Supercool water found near glaciers

Temperatures in Spitbergen, Norway may be below freezing, but the water around the Glacier Front isn’t frozen, researchers Eugene Morozov from Shirshov Institute of Oceanology, Aleksey Marchenko from the University Center in Svalbard, and Yu. D. Fomin from Moscow Institute of Physics and Technology, found,

This process of supercooling, also known as undercooling, happens when the temperature of a liquid or a gas drops below its freezing point without it becoming a solid. Experiments on Youtube show people taking liquid water out of their freezers, and pouring it on white plate under normal temperature. As the water hits the plate, it instantaneously turns into ice.

There are two methods for making water supercool. The first method, like the one show in Youtube videos, can only be achieved when water is extremely pure. Impure water has ‘nucleation sites,’ where water molecules gather and gradually solidify during the freezing process. People can make supercool water with a simple refrigerator and a bottle of pure water.

The other method relates to salinity and water pressure. Supercool water can occur under conditions of heat removal, different rates of heat and salt diffusion and rapid pressure decrease, chemists Valeria Molinero and Emily Moore in University of Utah found after much experimentation in 2011.

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Figure 1: Supercool water with no impurity. Source: BBC

With higher pressure, water will freeze at temperatures below 0 degree Celsius. In addition, higher salinity will also result in a lower freezing temperature. According to Figure 2, the freezing point will change depending on salinity and water pressure.

 

 

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Figure 2 Relationship between freezing point and Salinity/ Water Pressure. Source: London South Bank University

Previously, supercool water had only been created under laboratory conditions. However, the new findings from Eugene Morozov and his colleagues show that there is Glaciohydraulic supercooling water around the glacier that mixes and cools with high salinity and high pressure water.

The bottom of the glacier is approximately 15 m from the sea surface. The melt water (fresh water) flows from the glacier at a temperature of 0 C. After mixing with surrounding seawater with a temperature of – 1.8 C, melt water cools to temperatures lower than -1.8 C while ascending to the surface. As it surfaces, its temperature is close to the freezing point of seawater(-1.8 C). That temperature is lower than the freezing temperature of freshwater and its internal energy does not reach the equilibrium state required for freezing. This freshwater from glaciers cools to temperatures lower than freezing without becoming ice.

 

 

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Figure 3: Scheme showing freshwater flow from the glacier and measurement of water properties near the glacier front

The finding in Spitbergen is supported by research from Dr. Igor Dmitrenko, who works for Leibniz Institute of Marine Sciences at University of Kiel. He found that supercool water also exists in polynas, an area of open water surrounded by sea ice. However, this condition cannot be observed all the time since it cannot exist for an extended period. Supercooling water will transfer to the other states of water in a short time. It could play a crucial role in sea ice formation, researchers say.

“While frazil ice [needle-shaped ice fragments in water] formation in the Arctic was carefully examined over the past several years for the St. Lawrence Island and the Storfjord polynyas […] the processes controlling the sea ice growth due to supercooled water and frazil ice formation over the Siberian Arctic shelf remain poorly understood, owing to the scarce instrumental records and extreme climatic conditions,” Dmitrenko wrote in his study.  “From these considerations, supercooling might play a critical role in the shelf salt budget and sea ice production”

Check more information about glacier at Glacierhub.

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