Yes, we’ve had some pretty ornery weather this spring. We had a lack of winter, and then went right into summer temperatures. April showers were out to lunch, and the water table dropped 6 inches. We then got into record highs and that’s a bad combination. I don’t think this is news to anyone that’s been living outdoors, but what about the derecho?
Derecho is a unique wind storm. A band of fast moving thunderstorms with winds of at least 58 m.p.h. is a derecho. This is what we got across Ohio on a Friday in late June this year. It was large enough to effect several states and reach wind speeds of 70 – 90 m.p.h. and leave widespread tree and property damage. The power outages were massive and it’s all about a derecho.
This is an exaggerated form of a cold rain-filled front forcing warmer dry air up above it. When two fronts meet, wind is normal. The difference here is that the colder rain-cooled air was so widespread and fast moving that it caused the warm air to rise so rapidly and in such a widespread pattern. The storm just accelerated itself into practically a hurricane status of 80-90 m.p.h. in its microbursts and downbursts. I was in this storm and I saw things come apart and down that had been secure for 50 years.
What do you suppose actually fuels this weather machine? The real source of energy would be the sun. The Earth modifies the sun’s effect on our weather with tilt and rotation. Obviously, the sun’s rays heat the Earth’s surface and atmosphere. The Earth’s tilt and orbit causes the modification of season.
There are several constants. The Earth always rotates in an easterly fashion. The sun will always shine most directly at the equator. Warm air will rise toward the poles. Cold air at the poles receives the most indirect rays from the sun, and will drop toward the equator.
This constant rotation, rising, and dropping causes wind and weather. If the Earth remained stationary, the air would rise and fall directly with longitude. It starts with the sun, but is modified with the wind caused by our rotation. In simple terms, the weather is a giant mechanism which distributes the sun’s heat. For the most part, it’s a good system, but occasionally, it’s too much of a good thing. Now enter tornadoes, hurricanes, and derechos.
On an annual basis, the United States will experience 150 lightning deaths, 300 lightning injuries, and 10-15,000 forest fires from lightning. That is a lot of chaos, but if you understand that there are 1,800 thunderstorms going on over the Earth’s surface at any given time, maybe we’re lucky. Speaking of lucky, this would be an inappropriate nickname for Roy Sullivan, a retired park ranger. He has been struck by lightning 7 times. Maybe he is lucky that it didn’t kill him. You be the judge on that.
Some interesting issues on this wind thing are that in the Northern Hemisphere, winds whirl clockwise around highs, and counter-clockwise around lows. In the Southern Hemisphere it’s the reverse. Why? If the heat starts at the equator and moves toward the poles, and cold air moves from the poles on a ball that always rotates east, guess what? There’s your sign, the formula for any unknown is found by establishing constants and minimizing variables.
What about those variables? As the Earth turns and warm rises, while cool drops, in an easterly fashion, we call the resulting meeting place, the Gulf Stream in the Northern Hemisphere. You will hear many blame the weather or change in weather on the Gulf Stream. Trade winds in the Southern Hemisphere get the same notoriety. This is an effect. What was the cause?
This jet stream, in our neighborhood, travels from west to east, five to ten miles above us. It’s like a long waving ribbon, constantly waving north and south as it travels west to east. Why can’t it stay put? It’s all these highs and lows spinning in opposite directions, causing fronts to collide.
Ben Franklin helped identify weather movement, and Sam Morse’s telegraph helped reduce the surprises that the weather gives us. In 1870, the National Weather Service got up enough nerve to actually forecast the weather. The National Weather Service will collect data from thousands of stations daily, as well as from ships, aircraft and buoys, but remember this – a five day forecast is much less accurate than a two day forecast, and a thirty day forecast is a gambler’s hunch. You might as well go by last year’s almanac. There’s plenty of blame to go around for this spring’s ornery weather. Some would accuse Gulf Stream, fast women, slow horses, Adam and Eve, or The Serpent, but I would suspect that behind all the smoke and mirrors lies the Sun. All others are modifiers or casual effects.
We could ask Roy Sullivan. He’s been up close and personal with it more than most, but we might find his words rather shocking.