The skies lit up with a gorgeous array of rainbows after last evenings storms passed. Tony has the blustery and colorful story.
Mother of All Storms and Rainbows
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In case you missed it, the powerful squall line of winds that passed through our region on Tuesday afternoon was spawned by the “greatest inland” cyclone in the history of the USA. Only a few of the strongest hurricanes in our country's history (Camille 1969, Hugo 1989 and Labor Day unnamed storm of 1935 et al) exceeded the power of Tuesday's tempest.
Think of a cyclone as a wind storm with nasty intents. Locally the winds huffed and puffed with gusts as high as 40-50 miles per hour on Tuesday afternoon. Reports of felled trees from Carter Caves to Proctorville were common. One account of a funnel cloud from Laura Rodgers of Spencer was plausible. 'I took the kids to the basement" a weather savvy Laura told me. After all more than 20 twisters hopsctoched America's breadbasket on Tuesday as the storm front roared eastward.
On Wednesday, another dozen tornado sightings occured mainly in Virginia and the Carolinas. Said Eric Fossell, our Internet guru at WSAZ, "my sister in southern Maryland tells me twice this Wednesday evening there have been tornado warnings in St. Mary's County."
Closer to the storm center, winds in Minnesota, Michigan and Wisconsin topped to 60 and 70 miles per hour but with a twist. Those ferocious gusts lasted not minutes but hours on end over a two day period. Much of the Land of 10,000 Lakes and the Dairy State are still without power.
Late Tuesday, the central pressure of the storm that passed thru the upper Midwest saw the barometric pressure tumble to an epoch 28.23” (956 mb) of mercury in the Northern Minnesota.
Now meteorlogists are interested in pressure thanks to its special relation to the wind. The rule of thumb, the lower the pressure and the higher the difference in pressure (aka gradient) from point A to B, the stronger the winds.
While at Penn State I used my favorite equation to answer many a question while studying for my Masters. It is called the Continuity Equation and it describes eloquently how wind and pressure are intertwined. Namely,
dQ/dt + del dot Vector V= Zero
The Continuity Equation says that a column of air must conserve (leave unchanged) the amount of mass of air in the cylinder. If air rushes into the bottom of the cylinder, an equal amount must exit the top of the column. If air pours into the top of the column, then an equal amount must leave the bottom.
That's where Mother Nature sets the wind into motion. Take Tuesday! With the pressure falling all day east of the Mississippi, Mo Nature converted the lower barometetric pressures into stronger winds. In effect as pressures sank, the amount of air in the column tried to get lower and lower. To compensate for this "net column divergence", air rushed into the cylinder faster and faster.
Of course, you and I know that rush of air as wind. Better stated, a large vacuum cleaner or air was established that sucked air into the column. That's how wind is generated on the planet earth!
In addition, low pressure conjures up aches and pains for arthritis and rheumatism sufferers. In fact, Tuesday could go down as the single most painful day of weather related arthritis and bursitis in modern USA history.
Of course, when those wind storms spit out rain and are followed by sun, you get rainbows. And this week, the rainbow pictures have dazzled us. The enclosed shot is courtesy of Kevin Bonham of Proctorville.
Our next chance at a rainbow you ask? Not until next week as chilly but dry weather invades courtesy of the big storm which is now in Western Quebec Canada and moving away.