What type of ice is formed by the rapid freezing of small supercooled water droplets?

The formation of rime ice occurs when small supercooled water droplets come into contact with a surface and freeze rapidly upon impact. This process typically happens in conditions of moderate to severe icing, where the droplets do not have enough time to spread out before freezing. As the droplets freeze almost instantaneously, they create a rough, opaque texture that is characteristic of rime ice.

This type of ice tends to accumulate on aircraft airfoils and surfaces during flight in cloud conditions or in freezing drizzle, leading to increased drag and potential loss of lift, which is a critical component for pilots to understand for safety and performance reasons.

In contrast, clear ice forms from larger water droplets that can spread before freezing, leading to a smooth surface. Frost is the result of water vapor in the air crystallizing on cold surfaces, and hoar frost forms specific patterns of crystals due to temperature inversions or high humidity in cold conditions. Understanding the characteristics of each type of ice, especially rime ice, is vital for flight safety and flight planning in icy conditions.