ARS / US DEPT OF AGRICULTURE / SCIENCE PHOTO LIBRARY ARS / US DEPT OF AGRICULTURE / SCIENCE PHOTO LIBRARY
Snowflake. Coloured low-temperature scanning electron micrograph (LT-SEM) of a snowflake. To prepare for the imaging process the snow and ice crystals are collected on copper sample plates containing pre-cooled methyl cellulose solution. The plates are then rapidly cooled to -196 degrees Celsius in a bath of liquid nitrogen. The samples are then either held in storage or photographed using a field emission scanning electron microscope that has been pre-cooled to -170 degrees Celsius. Magnification: x38, when printed 10 centimetres wide.
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