Cumberland Times-News

October 1, 2013

Our skies unmatched in the solar system

Bob Doyle, Columnist
Cumberland Times-News

— In less than a year, our public planetarium programs will resume in the Multi-media Learning Center (MLC) in the CCIT building at Frostburg State. 
CCIT stands for Center for Communication and Information Technology. I am hoping to start our public programs with a review of recent weather events, illustrated by pictures of local clouds. 
For some of the most beautiful sights in nature, easily visible to the eye are the clouds that pass over us each day. The most striking space pictures are of nebulae (clouds) in deep space, taken by space telescopes and by special digital cameras on Earth. 
What’s ironic is that these celestial images are the products of long exposure imaging and near perfect guiding by telescopes. When one looks through a sizable telescope, only a pale glimpse of these images can be seen. 
The clouds over our heads don’t require special image processing and can be seen easily by eye. Yet so many of us scarcely notice these delicate sky tapestries. So our programs will reveal the beauty of our atmosphere and encourage us to be day sky watchers. 
In our solar system, the skies of the Earth are unmatched in beauty.
For Mercury, the asteroids, most moons of the planets and the dwarf planets don’t have atmospheres that allow cloud formation. Venus and the giant planets have dense cloud blankets. The planet Mars has gigantic dust storms. Saturn’s big moon Titan is swathed in a soupy smog of ozone and hydrocarbons. Only rarely would one spot Saturn with its rings from the surface of Titan.
Robert Matthews has a fascinating collection of questions titled “Q and A: Cosmic conundrums and everyday mysteries of science” published in 2005 by Oneworld publishers with ISBN 13:978-1-85168-449-6 (paperback)
(Conundrum in the subtitle refers to phenomena that have a surprising explanation.) I will consider a few of the meteorological questions that Matthews considers. 
Can one see a double rainbow? Ordinarily, there is just one rainbow seen. 
This requires that the sun be visible (to you) and that there be rain falling in the opposite direction as the sun. Then facing away from the sun, a rainbow is visible with red on top and beneath are orange, yellow, green, blue and a delicate violet on the bottom. 
The single rainbow is due to the sun’s light being reflected once at the back of many raindrops. The spreading of the colors are due to dispersion, the bending of light that varies by colors with red bent the least and violet the most. 
A secondary rainbow or double rainbow is due to the sun’s light being reflected twice within the raindrops. The secondary rainbow is quite delicate and surrounds the primary rainbow. It’s colors are reversed with violet on top and red on the bottom. 
How much rain does an inch of snowfall consist of (if the snow were to melt)? There’s no easy answer as there are different types of snow. An inch of the fluffiest snow is equivalent to one fiftieth of an inch of rain. 
This kind of snow is the easiest to shovel off your driveway or whisk off your car. Thick or moist snowfall is equivalent to one fourth of an inch of rain. This type of snow is difficult to shovel off a driveway. For ordinary snow, one inch equals one tenth of an inch of rain.
What is wind-chill based on? The wind-chill is based on how quickly one’s bare skin loses heat at a given wind speed and temperature. The latest wind chill formula, based on measurements and computer simulations tells us that a 20 mile per hour wind at 0 C (32 F) makes us feel as if it is -7 C or 19 F with no wind. 
SKY SIGHTS AHEAD: The moon is now a crescent in the southeastern dawn. Tomorrow morning the crescent moon appears near the planet Mars. On the evening of Oct. 4, the moon will swing from the morning to the evening side of the sun. Venus is a steady point of light low in the southwest and seen as early as 7:30 p.m. 
Bob Doyle invites any readers comments and questions. E-mail him at rdoyle@frostburg.edu . He is available as a speaker on his column topics.