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Snowflake -> Appearance -> Color

Aggregate snowflake development is dependent on ice crystal collisions. Together, numerous ice crystals combine to form one snowflake. Although ice by itself is clear, snow usually appears white in color and opaque - not transparent.

The unique configuration of multiple ice crystals constructing a single snowflake provides numerous surfaces upon which light can interact and scatter off of. Multiple scattering increases the reflectivity and thus the optical depth within the snowflake. As optical depth increases, more scattering can occur and the dependence on a particular wavelength within the visible spectrum decreases. Thus, instead of one particular wavelength, all wavelengths (colors) of the visible spectrum are reflected, producing its white appearance.

Additionally, the random arrangement of the individual ice crystals also produce it’s opaque appearance due to the multiple scattering enhancing the formation of a non-continuous medium.

While aggregated snowflake structures lend to the multiple scattering of light -- which determine the color and clarity of snowflakes, once on the ground, interactions such as algae growth can cause snow to exhibit different colors such as green or even red.

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