What is the main characteristic of the airframes affected by rime ice?

Rime ice primarily occurs when supercooled water droplets freeze rapidly upon impact with a surface, such as an aircraft's airframe, which is flying through clouds containing these droplets. The key characteristic of airframes affected by rime ice is indeed rapid accumulation. This phenomenon typically happens in conditions where the ambient air temperature is below freezing, and the droplets are large enough to freeze instantly on contact, leading to a build-up of ice that can obstruct airflow over wings and control surfaces.

In contrast, rime ice does not develop slowly because that would suggest a different icing mechanism, such as glaze ice, which forms under different conditions and tends to accumulate more gradually. Additionally, rime ice significantly impacts aircraft performance and safety by adding weight and changing the aerodynamic properties of the airframe. Furthermore, it commonly occurs at temperatures less than 0 degrees Celsius, which aligns with the understanding of how and when supercooled water behaves.