Preserving Snowflakes

Under the microscope, I found that snowflakes were miracles of beauty; and it seemed a shame that this beauty should not be seen and appreciated by others. Every crystal was a masterpiece of design and no one design was ever repeated. When a snowflake melted, that design was forever lost. Just that much beauty was gone, without leaving any record behind.
- Wilson 'Snowflake' Bentley, 1925

Wilson A 'Snowflake' Bentley

Wilson A Bentley (1865 - 1931) was a self-educated farmer from the small rural town of Jericho, Vermont, USA. He performed pioneering work in the field of photomicrography1, and he is particularly renowned for his work with snow crystals (snowflakes). In 1885, he became the first person to photograph a single snow crystal, and in 1931 his book Snow Crystals (containing nearly 2,500 images of snow crystals) was published by McGraw-Hill.

Snow

Snow consists of minute ice-crystals that are formed by the freezing of water vapour in the atmosphere. The crystals appear white because of the reflection of light from a myriad of tiny surfaces. Snowflakes form when both the air temperature and water vapour content are very low. They take the form of six-sided plates which may be less than a millimetre in diameter. Usually, however, they take on more complicated shapes, though these always have an underlying hexagonal structure.

Large snowflakes form when the snow falls through a warm layer, causing smaller crystals to fuse together.

You can preserve your own images of snow crystals by following the procedure below.

You Will Need

• Snowflakes

• Small sheet of chilled glass

• Hairspray

• Refrigerator

Method

1. Chill your hairspray and sheet of glass in the fridge and wait for it to start snowing.

2. Spray the sheet of glass with the cooled hairspray and take it outside into the snow.

3. Collect some snowflakes onto the surface of the glass.

4. Take it back inside and allow the snowflakes to thaw (this will take about 15 minutes).

5. You will now have a permanent record of the snowflakes that you caught.

• A typical snowflake falls at a velocity of about two feet/second (four mph). Hence a snowflake takes about eight minutes to fall 1,000 feet (305 metres).

• There are five different basic shapes of snowflake.

• Following the publication of Wilson A Bentley's book, Snowflakes in 1931, it was often asserted that no two flakes are identical. However...

• In 1988, an American meteorologist discovered two flakes that did appear to be identical.

• When snowflakes land on water they emit a high frequency 'scream'. This arises from trapped air bubbles which vibrate at a rate of 200,000 times per second (200 kHz)

1Photomicrography is the art of taking photographs through a microscope.