What characterizes rime icing compared to clear icing?

Rime icing is characterized by its formation from small water droplets that freeze rapidly upon contact with an aircraft surface. This type of icing typically occurs in conditions where there are lower temperatures and smaller droplet sizes, hence it forms when the liquid water droplets are small and have low kinetic energy. When these small droplets hit an aircraft, they quickly freeze, solidifying into a rough, opaque layer of ice.

The presence of low catch rates also underlines the conditions under which rime icing develops. Low catch rates mean that the aircraft is not collecting a significant amount of larger water droplets, which aligns with the behavior of rime icing. The combination of small droplet size and low catch rates distinguishes rime icing from other types of icing, particularly clear icing, which consists of larger droplets that accumulate more slowly and are associated with supercooled liquid water in conditions that allow for more substantial accumulation.

In contrast to rime icing, clear icing is formed from larger droplets and is typically associated with higher catch rates, making it smoother and more dangerous due to its weight and potential impact on aircraft performance.