Hexagonal Plate Snow Crystal With Rime

December 25, 2017


Image Made at the Electron and Confocal Microscopy Laboratory, at the Beltsville Agricultural Research Center
Summary Author: Jim Foster

Photographing snow crystals is challenging not only because they're so fragile but because in the process of collecting them and mounting them on a viewing stage, they often melt beforehand. When employing scanning electron microscopy (a low-temperature, scanning electron microscope) to image snow crystals, such as this simple, hexagonal plate crystal with rime (magnified here at approximately 85 x), the crystals are first softly scrapped onto metal copper plates that have been pre-cooled with a methylcellulose solution. Once a crystal is on the sample plate, it's quickly plunged into a dewar of liquid nitrogen, which rapidly cools the crystal to -320 F (-196 C), leaving it affixed to the plate and ready for viewing, even weeks later. Note that the rime, prominent on the edges of the crystal featured above, is frozen cloud droplets The first snow crystals to be observed using this approach were collected at the Beltsville Agricultural Research Center, Maryland, in the mid 1990s. 

Merry Christmas, Happy Holidays and Happy New Year

from the Staff of the Earth Science Picture of the Day

Erin Senoz, Stu Witmer, Jim Foster