Vail Daily column: Thank the clouds for winter’s return
Winter is here! It’s time to thank the nimbostratus for our fluffy white playground’s return! Patiently, we’ve waited for this snowfall for it has been hidden in secrecy for many months. This mystical force of nature is very particular about conditions and has a rigid arrival plan. Luckily for us, when it snows, it dumps!
Have you guessed it yet? The mighty nimbostratus is a dense, thick and layered cloud which precipitates light airy snow. It appears to be gray and terrifying, but under its facade is a whiteout in the making. This middle layer cloud is filled with ice crystals and snow because of condensation happening below the freezing point. Covering the entire sky, this cloud resembles a frosted blanket with no edges or defined shape.
What makes this cloud such a natural phenomenon, however, is the process by which it makes snowy goodness. Most clouds are made via the lifting and cooling of moist air, known as condensation. The nimbostratus is unique in the fact that it is associated with a front. The progression of cloud types and rate of development and thickening is a good visual indicator of an oncoming front. In the event of a cold front, cirrus stringy and high clouds are seen first. At the frontal zone, where the cold air is moving south, a deep nimbostratus cloud is formed. Following the front, cumulonimbus clouds form. These clouds have extreme vertical development and bring intense intermittent precipitation with gusty winds and often thunder. On the other hand, a warm front occurs when warm air is forced north. After the first cirrus clouds are seen, middle level alto clouds fill the sky, thickening and lowering down. This is when low-level stratus clouds and often fog emerge with widespread precipitation. As the warm front continues to advance, the nimbostratus begins to make an appearance. Here we can see a shift in precipitation as it becomes showery and persistent.
Thus, in order to cover our idolized mountain slopes, conditions must be on point. The right amount of cold polar air must be pushed down from the north, while at the same time relatively warm moisture laden air is needed from the south. With such dynamic weather patterns during this season, precipitation could be rain, snow, sleet, freezing rain or all of the above. At cloud level, precipitation starts out as ice or ice crystals. As it falls, the temperature in the air dictates what form it will be in as it lands on the ground. If temperatures are below freezing in all or most of the atmosphere, then the glorious six-sided ice crystal known as snow will float from the cloud to the ground. This stuff is the real deal; snow makers can’t imitate anything like it!
Elevation is Everything
Due to the geography as well as the elevation of the valley, winter precipitation generally falls as snow — whew! Lower elevations are generally more at risk for freezing rain and ice storms because cold, dense air settles. This means that rain will freeze on anything it contacts, such as roads, bridges, overpasses, power lines and trees, making winter travel extremely dangerous.
Colorado’s winter climate is truly divine. With an average annual snowfall of 350 inches, it’s no wonder why Vail is considered an extraordinary ski and snowboard destination around the world. This place I call home sure wouldn’t be the same without those frosted peaks. And let me tell you, when the early sun touches those peaks, breaking through misty stratus clouds … well that is just one of Earth’s beautiful masterpieces that is better left a mystery.
Morgan Ballinger is an avid cloud watcher who attempts to forecast winter weather and relishes in the mystery behind science.