\n
![\"\"](\"https:\/\/blog.kootenay-lake.ca\/wp-content\/uploads\/2015\/12\/snowboundary151213s.jpg\")
<\/p>\n<\/p>\n
If one is walking through a whitened forest on a mountainside, it is easy to tell if the trees are covered with snow or rime. From a distance, though it is often\u00a0more difficult as details vanish and both merely look white.<\/p>\n
Following my last posting about the appearance of the snow to rain transition in the air, it seemed appropriate to treat the transitions on the surface which can be seen with either fresh snow or fresh rime. Later in the season, the whole mountainside will be covered with snow and the transitions I discuss here will not be evident.<\/p>\n
The first picture shows snow on the mountainside. Snow is made up of large ice crystals that fall from the cloud. When they fall below the melting level in the atmosphere, the smaller ones melt quickly while the large ones keep falling a bit farther. The result is that the transition between snow and no snow on the mountainside is gradual.
\n<\/p>\n
Rime comes about in a different way. A cloud of water drops has been drifting alongside\u00a0the mountain. Some of the cloud drops bump into tree branches and are collected. Below the melting level, the droplet temperature is above 0 \u00b0C and the drops merely wet the tree. Above the melting level, the droplet temperature is below 0 \u00b0C and is thus\u00a0supercooled. When that droplet hits the tree, it promptly freezes to give rime. \u00a0The visual consequence is a rather sharp transition from no rime below the 0 \u00b0C isotherm to rime above that looks different than the gradual transition resulting from falling snow.
\n![\"\"](\"https:\/\/blog.kootenay-lake.ca\/wp-content\/uploads\/2015\/12\/rimeline141225s.jpg\")
<\/p>\n","protected":false},"excerpt":{"rendered":"
If one is walking through a whitened forest on a mountainside, it is easy to tell if the trees are covered with snow or rime. From a distance, though it is often\u00a0more difficult as details vanish and both merely … Continue reading