Accretion (meteorology)

Accretion is defined as the gradual collection of something over time. In meteorology it is the process of accumulation of frozen water as precipitation over time as it descends through the atmosphere. The collection of these particles eventually forms snow or hail in clouds and depending on lower atmosphere temperatures may become rain or sleet. Accretion is the basis for cloud formation and can also be seen as water accumulates on the particulate matter and form jet contrails. This is because water vapor in the air requires condensation nuclei to form large droplets of solid or liquid water.

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