Description
Supercooled water — liquid water maintained below its freezing point by the absence of nucleation sites instantaneously freezes when nucleation is initiated, the crystallisation front propagating outward from the nucleation point at approximately 1–10 cm/second depending on the degree of supercooling. This image captures the nucleation front at approximately 3 seconds after initiation in water supercooled to minus 10 degrees Celsius in a shallow flat dish. The crystallisation boundary — the advancing front between liquid water (dark, smooth surface) and ice (white, opaque surface) — is clearly defined as a circular ring expanding outward from the upper-right nucleation point. The ice formed is not clear but opaque, as the rapid crystallisation traps small air bubbles and creates a polycrystalline structure that scatters light. Shot at 1/1000 second overhead with backlight, the ice boundary appears as a bright white-edged circle against the translucent water background.
