Winter World_ The Ingenuity of Animal Survival - Bernd Heinrich [8]
Prior to Bentley, scientists and naturalists had commented on the structure of snowflakes, marveling less at their variety than at their six-cornered shape. In 1610, Johannes Kepler (famous for many discoveries, including the planets’ elliptical and not circular paths) is credited with first questioning why, whenever snow begins to fall, its initial formation invariably displays the shape of a six-cornered starlet. I’m not sure we have the answer now, but I assume that the six-arm configuration somehow relates to the most economical way that water molecules align when forming the crystal, when that crystal is free to grow in all directions in the air.
At the age of seventeen, Bentley merged the powers of his microscope with that of the newly developed camera, to realize his dream of capturing images of the snow crystal’s beauty. In a near miracle his father consented to pay the one hundred dollars it cost to purchase the elements required to fashion a primitive camera. Bentley struggled for weeks, experimenting, before on January 15, 1885, he developed the world’s first photo-micrograph of a snow crystal, in the woodshed of the family farm.
Bentley eventually needed to share his photographs with someone who might appreciate them, so he traveled ten miles down the road from his farmhouse to the University of Vermont in Burlington to see Professor George Henry Perkins, a biologist, ecologist, and longtime teacher there. Professor Perkins was amazed at the quality of Bentley’s work and told him that he absolutely had to write about it and show his snowflakes to the world. Bentley went back home and tried to write, but gave up in frustration. He went back to Perkins, appealed to him to put words to his photographs, and in 1898 an article by W. A. Bentley and G. H. Perkins titled “A Study in Snow Crystals” appeared in Appleton’s Popular Science Monthly. Perkins, not only a scholar but also a gentleman, wrote that although he put the pages together from Bentley’s notes and photographs, the “facts, theories, and illustrations are entirely due to [Bentley’s] writing and enthusiastic study.”
The article launched Bentley’s lifelong career studying snow crystals; it apparently unlocked his writer’s block as well. He went on to write fifty popular and technical pieces on snow, culminating with a book, Snow Crystals, in 1931, the year of his death, in which he published more than 2, 500 of his 5, 000-plus photographs.
A snow crystal is only the beginning of what makes snow. Snow flakes are composite masses of often hundreds of snow crystals that have collided on their long journey down from the clouds. The final size of a snowflake before it comes to rest depends on various factors including the numbers of crystals issued per cloud, the distance traveled, and the temperature. Snow falling early in the winter usually forms the largest flakes. Later in the season, when temperatures are lower, the ice crystals spawned by the clouds adhere to one another less readily. These crystals in colder air are brittle and constant collisions on the way down degrades them or smashes their intricate and beautiful structures. Arms of the crystals break off, and these tiny ice spicules then make up the snow. Driven by the wind, the ever more degraded crystal fragments are then packed into a tightly interlocking lattice on the ground that at low enough temperature, near -30°C, has the texture and appearance of Styrofoam. Indeed, walking on such snow at -30°C or less has the feel, and produces the sound, of walking on Styrofoam. It is the building material that is carved into blocks and has been used for centuries to construct winter homes.
Packed snow has superb insulating properties. An igloo efficiently retains warmth generated by a small oil-lamp and human bodies, while it effectively blocks the infinite heat sink of the sky above. Wind