Pat Shingleton: "Fog, Smog and... Snowflakes..."
Our episodes of fog traditionally limit visibilities along our coast and adjacent waterways. In October, 1948, smog filled the Monongahela Valley in western Pennsylvania as damaging oxides of nitrogen, halogen acids, zinc and lead claimed 20 lives with 2,000 afflicted with respiratory disorders. Fog and industrial pollution created the worst episode of smog in London from January 5th through the 9th in 1952. Stagnant air over the four day period found sulfur dioxide and particulate concentrations reaching deadly levels. The smog was so thick that Londoners couldn't see their hands with outstretched arms. Other complications included traffic jams with reports that only the blind could navigate. Nearly 100,000 residents became sick with deaths from bronchitis and influenza increasing ten times resulting in 4,000 fatalities. Four years later, Parliament enacted the British Clean Air Bill as the burning of bituminous coal was banned. From fog to a marvelous weather phenomena - snowflakes. Some of our residents enjoy family trips to various ski resorts. Snowflakes are single crystals of ice. It can be an individual snow crystal, a few stuck together or puff balls. A typical snowflake is 0.05x1.5x1.5 millimeters in size. If a snowman is around a cubic meter, it would take ten billion snowflakes to make one. A snowflake weighs about a hundred-millionth of a pound or 10 to the power of 8 kilograms. The reason snow is white because light travels from air to ice and from ice to air thus reflecting some of the light. Light shining into the snow gets scattered many times and once it scatters back out the light we see is white. No two snowflakes are alike. On rare occasions we receive a few flakes and some ice pellets. Weatherwise magazine reports that it is very unlikely that two snow crystals will look exactly alike. A water molecule is complex and not all water molecules are the same. A typical snow crystal could contain 1,018 water molecules with 1,015 of these different from the rest. As these molecules are scattered throughout the snow crystal, the unique design is created. As a snow crystal grows, the external conditions constantly change as it falls through the atmosphere. Its final shape is determined by its growth history as it descends. Years ago, scientists at California Institute of Technology used a vapor diffusion chamber to artificially create unusually shaped flakes as the "growing of snowflakes" continues.