We are experiencing some wonderfully foggy conditions today. Fog is this librarian’s very favorite weather. I love the way it changes the look and feel of everything around you and the mystery that it holds. It’s somewhat like reading a good mystery novel, when you can’t quite make out what’s ahead.
Fog is a weather condition that results in very low-lying clouds, made up of suspended water droplets. It forms when the difference between air temperature and dew point is less than 4 °F. An area the size of an Olympic sized swimming pool contains about 2 pints of water. Besides just looking really cool, all of this moisture in the air can be environmentally useful. The Redwood forests of California get around a third of their moisture from fog. In desert areas, fog can serve as a source of moisture when nets are used to collect the droplets from the fog.
Here a few other interesting facts about fog:
- The foggiest place on Earth is Grand Banks off of the coast of Newfoundland, where the cold Labrador Current mixes with the warmer Gulf Stream. The area sees over 200 foggy days per year.
- Shadows that are cast through fog are three dimensional.
- Foghorns use a low-pitched tone because low-pitched notes lose less energy to water droplets than high-pitched ones and thus travel further.
- Fog can be both good and bad for your skin. The moisture in fog acts as a natural emollient for your skin. But, even though fog blocks visible light, you may not realize that it does let through the ultraviolet light that causes wrinkles and sunburn.
- Fog affects our perception of speed. Because of reduced visibility we should drive more slowly and in fog we have to be extra careful to do so. Since the fog obscures our surroundings, our brains don’t perceive the contrasts in the objects around us as well and thus we think we are going slower than we actually are.
- Be sure to use your low beam headlights when driving in foggy conditions. High beams will be reflected back at you in the fog, making it even harder to see.
- Fog helped us win the Revolutionary War. At the Battle of Long Island, on August 27, 1776, George Washington and troops were beginning to be surrounded by British forces and needed to retreat. A heavy fog rolled in and provided cover for just long enough for the retreat of 9,000 Americans. When the fog lifted, the British moved into the area to find it empty.