Winter Hydrometeor Classification Ground Truth Program

Project Status: Active 5 Mar 2008 -- A potentially major winter storm is in the offing, perfectly situated in the project observing area. The event will likely start with rain, then change to sleet, ending finally as snow. There may be a brief period of freezing rain, but only a little. Much more important will be snow amounts. Capturing the change form rian to snow is important, so as soon as the change occurs, please log your observations.

Snowflake Identification

Looking at snowflakes is more than simply a pleasant pastime: the shapes and structure of snow crystals tell us a great deal about the conditions under which the crystal formed: How cold? Did the crystal growth occur in more than one temperature regime? How moist were the conditions? Did the crystal fall through cloud after it formed, or did it fall mainly though clear air? These are a few of the things that can be learned by studying snow crystals.

Because we've received some questions about this, we decided to make an out-of-print snowflake identification manual ( 1.5 MB) available online. Simply click the link and you will be able to see (and save) the manual in PDF format. (If you don't have the Adobe PDF reader, it's available as a free download here .)

Feel free to report crystal types with your observations, using the "address" window for this, as well as for your additional comments about your observations. This works especially well if you provide your location in latitude and longitude, because it leaves more space for your comments and crystal type reports.