Supercooling, also known as undercooling, is a fascinating phenomenon in which a liquid is cooled below its freezing point without solidifying. This process occurs in the absence of a seed crystal or nucleus around which a crystal structure can form[1]. For instance, water can be supercooled down to -48.3°C without any special techniques, such as chemical demineralization[1]. Supercooled water can naturally exist in various environments like the atmosphere, animals, or plants[1].
When a liquid surpasses its standard freezing point, it typically crystallizes in the presence of a seed crystal, forming a solid structure. However, without such nuclei, the liquid phase can persist until the temperature at which crystal homogeneous nucleation occurs[1]. Homogeneous nucleation can happen above the glass transition temperature; if it hasn’t occurred by then, an amorphous (non-crystalline) solid will form[1].
One practical application of supercooling is in refrigeration. Freezers can cool drinks to a supercooled state so that upon opening, they turn into slush[1]. An example is special vending machines that stored beverages in a supercooled state, causing their content to turn into slush upon opening[1].
Supercooling allows liquids to reach temperatures below their theoretical freezing points without ice formation[2]. This process is crucial for various applications and scientific studies. For instance, supercooling has been used in weather modification to dissipate supercooled clouds by seeding them with dry ice particles to induce ice crystal formation and precipitation[4].
In a scientific demonstration involving supercooling water, a flask of liquid water below 0°C was created and seeded with dry ice to initiate instantaneous freezing[5]. The setup involved specialized apparatus like a cleaned filter flask and precise cooling procedures using acetone baths and salted ice-water baths to achieve supercooling conditions[5].
Legend has it that some lakes in Switzerland are supercooled, where casting a stone into the water supposedly instantly freezes it. Despite the challenges and complexities involved in artificially inducing supercooling, nature seems to effortlessly achieve this phenomenon in certain natural settings[5].
Supercooling opens up avenues for exploration in various fields, from fundamental physics to practical applications like refrigeration and weather modification. Understanding this process not only sheds light on intriguing natural occurrences but also paves the way for innovative technological advancements.
Citations:
[1] https://en.wikipedia.org/wiki/Supercooling
Supercooling, also known as undercooling, is the process of lowering the temperature of a liquid below its freezing point without it becoming a solid. As per the established international definition, supercooling means ‘cooling a substance below the normal freezing point without solidification’ While it can be achieved by different physical means, the postponed solidification is most often due to the absence of seed crystals or nuclei around which a crystal structure can form. The supercooling of water can be achieved without any special techniques other than chemical demineralization, down to −48.3 °C (−54.9 °F). Supercooled water can occur naturally, for example in the atmosphere, animals or plants.
