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Best Ice Crystals

Dendrites grow faster than other ice crystals. Their feathery and complex tree-like branches provide a higher surface area for growth. Their structure is easily fractured which increases the number of ice particles that can serve as nuclei for more ice crystals to grow. Snowflakes composed of dendritic crystals accumulate loosely on the ground, especially with light winds, resulting in lower snow to liquid ratios. All of these characteristics usually result in higher snowfall accumulation rates compared to accumulation rates of snowfall dominated by other crystal habits. Cloud temperatures in the -12 to -18 degrees Celsius range favor dendritic crystal growth.

Weather forecasters can use vertical cross-sections of the atmosphere depicted in numerical forecast models to see where vertical motion, moisture, and favorable crystal growth temperatures overlap. Looping the sections over time (time sections) can give an idea as to how long the conditions may last over a specified location.

A strongly dendritic snowfall composed of big flakes with large loosely attached dendrites and near calm winds occurred in Green Bay, WI on December 23, 2000. The storm produced 5.5 inches of snow from only a tenth of an inch of liquid. That is a 55 to 1 snow to liquid ratio.

For a comprehensive discussion of other influences on measured snowfall amounts, read the "How Much Accumulation?" discussion.

More information

"A Quick Review of Snow Microphysics And Its Relation to Heavy Snow Forecasting" - Greg DeVoir, NWS CTP Winter Weather Workshop, November 7, 2002

"How Much Accumulation?" - A discussion by the author of this website (view)

More than what most (except us) want to know about ice crystals, snowflakes, and beyond - SnowCrystals.com