This photograph illustrates two snow crystals which, if not identical, are certainly alike. The crystals were collected on a glass slide coated with oil, exposed for 11 seconds at the end of a rod extended from the King Air aircraft (owned by the National Science Foundation and operated by the National Science Foundation). The King Air was flying between two layers of cirrus cloud over Wausau, Wisconsin, as part of the First International Satellite Cloud Climatology Project Regional Experiment. The paired crystals (lower center) are exceptionally thick, hollow columns. Both feature internal structures that are markedly asymmetric. The difference in the ends of the hollow columns suggests that they fell lengthwise, and the slightly greater growth of the left halves suggests that they were the lower ends. They probably grew attached together. The columns are roughly 0.01 inch (0.025 centimeter) long and 0.007 inch (0.017 centimeter) wide.
