biogenic ice nucleus

meteorology

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July 19, 2026

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A biogenic ice nucleus is a particle that, when present in supercooled water, triggers the growth of an ice crystal around itself. Most atmospheric ice crystals are believed to form on these nuclei.1

The decomposition of organic matter is a primary source of biogenic ice nuclei. These nuclei can cause ice formation at temperatures as warm as -2 to -3 °C (28.5 to 26.6 °F). The temperature at which freezing occurs varies with biome and latitude, with warmer freezing temperatures found above the Arctic. The formation of ice releases energy, increasing air buoyancy and promoting convection, cloudiness, and precipitation. Biogenic materials also favor charge separation, which can lead to lightning.2

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Biogenic ice nuclei
As water vapour condenses onto condensation nuclei, the droplets grow in size. Growth proceeds at relative humidity as low as 70 percent, but the rate of growth is very slow. Growth by condensation is most rapid where the air is slightly supersaturated…
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As water vapour condenses onto condensation nuclei, the droplets grow in size. Growth proceeds at relative humidity as low as 70 percent, but the rate of growth is very slow. Growth by condensation is most rapid where the air is slightly supersaturated…
Read More