What's with the warm weather?
According to Environmental Science Prof. Robert Davis, the jet stream is to blame for the balmy temperatures.
Without getting too technical, the jet stream essentially separates cold arctic air from warm tropical air.
During most winters a jet stream trough, or southward bulge in the jet stream that meanders across the northern hemisphere, settles in over Virginia, keeping the warm southern air at bay while Canadian air masses invade from the North.
But "this winter, the jet stream has mostly resided much farther north, over New England or even southern Canada, than its typical summertime position," Davis said.
This ridge in the jet stream, or northward bulge, allows warm air to creep up the eastern seaboard. This year the ridge brought record-breaking high temperatures to Virginia and much of the East Coast.
Lest anyone pronounce Old Man Winter dead, Virginia has experienced warm spells before, only to see the cold weather return the following year.
In the winter of 1932, temperatures between December and February exceeded long-term averages by more than nine degrees, reaching a sultry 87 degrees in Roanoke.
University climatologist Patrick Michaels cautions those seeking to attribute the soaring mercury to global warming. Although rare, these temperature oscillations are perfectly normal, and should not spark alarm.
"There are no trends in Virginia climatology records to support global warming. We have shown that the largest warming has occurred in the coldest air masses, such as in Eurasia, but we have not noticed any warming trends in the Southeast. It just does this," Michaels said.
How is artificial snow made?
Actually, snow making is pretty simple. Nature's variety consists of water vapor that condenses at cold temperatures on tiny dust-like particles called nucleators.
Although most precipitation begins as snow, only cold ground temperatures can ensure that it ever reaches the slopes.
Thus, ski resorts turn to snow making machines to make up for winter's neglect.
"Without artificial snow, we wouldn't have a ski season around here. Our average of 35 inches of snow a year just isn't enough to make a good base," Massanutten ski manager Steve Showalter said.
Snow making machines, or snow guns as they commonly are called, basically duplicate Mother Nature's work using sophisticated technology.
The guns produce snow by taking nucleator-treated water and spraying it onto the ground with highly compressed air.
Water is fed via a hose into the rear of the snow gun, where it is combined with pressurized air from a compressor.
There the compressed air atomizes, or mixes, the water so that it breaks into many smaller droplets. Upon release, these droplets condense as ice crystals on the nucleators and fall to the ground as snowflakes.
The result? A great day on the slopes - at least in theory. Though the process sounds simple enough, getting the snow to form can be quite complicated.
Only temperatures well below freezing guarantee a decent blanket of snow. Otherwise, ski resorts must consider the air's relative humidity before flipping the switch on their machines.
Water vapor condenses more readily in low humidity. This allows snow to form at higher temperatures.
In higher humidity, however, the air already is saturated with water vapor, so the additional water has trouble condensing.
In other words, unless the mercury drops well below 32 degrees Fahrenheit, humidity can thwart even modern science's best efforts and spoil a day of skiing.
- Compiled by Mike Layfield
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