At this time of year on warm, humid nights, the phenomenon known as “heat lightning” is very common. The sky will seem to flicker with light; and even on a seemingly clear night with stars, you may see flashes. No sound accompanies the flash, although if you are listening to an AM Radio you’ll hear crackles of static at the same time you see the flash.
What you’re likely seeing is the light from a distant thunderstorm that is located at too great of a distance for the thunder sound to be heard. The sound of thunder rarely travels more than 10 miles. Other cases can be explained by the refraction (or bending) of sound waves by bodies of air with different densities. An observer may see nearby lightning, but the sound from the discharge is refracted over their head by a change in the temperature, and therefore the density, of the air around him. As a result, the lightning discharge seems to be silent.
The term “heat lightning” probably comes from the fact that the effect is most often seen on warm, humid nights during July and August. So an association has been made with sultry temperatures. But when the sky is hazy, as is quite typical on warm, summer nights, the light from intense thunderstorms as far away as 100 miles can be reflected off a layer of haze and up into the night sky.
And that’s why you tend to see heat lightning as just a diffuse flash or flicker.
January 7, 2008 …The tornado started at 3:30 pm about 1.2 miles north of Poplar Grove in Boone county and ended at 3:48 pm about 3.2 miles north northeast of Harvard in McHenry county, Illinois.
The first signs of damage were at Quail Trap road where trees were damaged and sections of roofing were removed from a shed. A large barn was destroyed and other buildings were severely damaged. Large trees were snapped or uprooted. The tornado reached its maximum intensity of EF3 at the northeast corner of Centerville road and Beaverton road. A two story farm house and garage were leveled and large trees were stripped of all branches. The tornado was about 100 yards wide through this area.
There was damage to trees, power lines, barns, and sheds. The tornado then crossed the Boone/McHenry county line as a weak EF0 tornado with just minor tree damage at this point. It crossed Hunter road and continued to track northeast across Ryan road as an EF0 and caused mainly minor tree damage. It crossed White Oaks road then it uprooted a hardwood tree and snapped off pine trees at their base along Maxon road. The tornado intensified as it moved toward the town of Lawrence where it produced the worst damage. Significant damage occurred in the town of Lawrence particularly at a house that had more than half of its roof ripped off and garage blown out.
The tornado then moved across the Chicago and Northwestern railroad where it blew 12 railroad freight cars off the track. The train was moving at the time the tornado hit it…so as the main engine stopped…the remaining cars on the track continued along it and slammed into the front part of the train. This caused a few more cars to derail…including one containing hazardous materials that caused the evacuation of the town of Lawrence.
As the tornado moved east of Lawrence it once again started to weaken with some tree damage and shingles off of a few houses on the northeast side of town. It then ran along Oak Grove road for a stretch where it produced EF1 damage with a hardwood tree snapped at its base and knocked over an old…weakly structured barn with estimated winds around 100 mph. It then headed across farm fields and headed for hwy 14 where it damaged a metal barn and sheared a few trees. As it crossed highway 14 it flipped a semi-trailer and injured the driver at a truck stop weigh station.
Once again, we have had to deal with a tropical system dealing us a direct hit. This time it was only a tropical storm and it came up from the south. There was a lot of rain and brief gusts that were close to, if not at, hurricane force.
Now comes the long process of cleaning up all the yard waste that was thrown around. But first, we have to wait for the water to go away. Mid-day numbers indicated over 7 inches of rain since the storm first started affecting us yesterday evening.
Fay managed to maintain its strength as it traveled up the state. Fourteen hours after making landfall at Cape Romano, Fay’s central pressure has dropped and the winds have increased. The forecasts call for it to exit Florida around Melbourne and re-enter the state around Jacksonville.
Keep an eye on this storm, it’s going to be around for a while.