sn❄wtool App NEW!

HOW TO USE THE APP

The first thing we often do when we look at complicated things is break them down into categories. With snow, we first divide the crystals into atmospheric forms and those found in the snowpack. Atmospheric forms are primarily divided by shape. Thus, we have atmospheric categories such as stellars, plates, needles, etc. Snowpack forms are primarily divided by process: kinetic, equilibrium, melt-freeze, etc. 

International committees have agreed on a nomenclature that serves this purpose. We use this protocol in our SnowTool app to make things easier for you and to maintain consistent communication between people and organizations. 

The International Classification for Seasonal Snow on the Ground details a recognized classification that divides both atmospheric and snowpack forms first by main classes, then further by subclasses. Both are represented by two-letter codes, the atmospheric forms are given a main class of PP for precipitation particles and have many subclasses, such as stellar dendrites sd, plates pl, etc.

A full description of a grain might then be PPsd, PPpl, etc.  Although there is only one main class for atmospheric forms PP, there are eight separate main classes for snowpack forms, including common classes such as facets FC, rounded grains RG, and melt forms MF. Numerous subclasses for snowpack forms exist, such as small round sr and large round lr for rounded grains; these would be labeled RGsr and RGlr, respectively.

We encourage you to pay attention to the major classes first (two-letter capital code). Get comfortable with those, then add in the subclasses with time ((two-letter, uncapitalized code).  It will be obvious which major class and subclasses to learn, because these will be the ones you are most frequently exposed to in your field observations. Note that the subclass is never used without the major class.

We use categories to simplify and communicate. Note that because the snowpack is ever changing, you are really observing a structure (snowpack stratigraphy) and its parts (grains and crystals) that represent a continuum. A faceted grain may be rounding or a round grain may be faceting. Some grains may not easily fit into simple categories or may show characteristics of more than one shape or process.  Be patient - you'll figure it out. After more than 40 years of looking closely at snow grains, I continue to see new things on a regular basis. It's one of the reasons this stuff is so interesting.

There is also a symbol set that goes with the major classes and subclasses. We use symbols too in most cases on the SnowTool app. It is appropriate to use major and subclass symbols, but it is also fine to use just the subclass symbol for a given grain.

This is the first release of the sn❄wtool App. Check back often as we will add more images and features to provide more education and utility.