ABSTRACT
The formation of ice on land structures may derive from cloud droplets, raindrops, snow, or water vapour. Here the term cloud droplets implies droplets in clouds observed locally as fog; they are smaller than raindrops and have a lower fall velocity. The effects of water vapour condensation (hoar frost) have been shown to be usually negligible compared with growth rates of ice from impingement of liquid water droplets and snow particles (Makkonen, 1984a).
