Ice crystals grow through two primary mechanisms: the freezing of super-cooled water droplets and deposition. According to available information, both processes require a nucleus.
Two Main Methods of Ice Crystal Growth
Ice crystals don't just spontaneously appear. They need a little help getting started. Here's how they grow:
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Freezing of Super-cooled Water Droplets: This occurs when water droplets that are colder than 0°C (but still liquid, i.e., super-cooled) freeze into ice crystals.
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Deposition: This is when water vapor directly transforms into ice without first becoming liquid water. Just as condensation needs a nucleus, so does deposition, which requires a nucleus to initiate ice crystal formation.
The Necessity of Nuclei
A nucleus is a tiny particle that acts as a surface for ice crystal formation.
- Why are nuclei important? Water molecules need something to latch onto and organize themselves around to form a stable ice structure. The reference says that ice crystals must form around some nuclei.
| Growth Method | Description | Nucleus Requirement |
|---|---|---|
| Freezing of Super-cooled Water | Supercooled water droplets (below 0°C but still liquid) freeze. | Yes |
| Deposition | Water vapor directly changes to ice. | Yes |
