With the heat of the spring and summer, one of the most feared weather windstorms....the tornado. I hate the thought that one would ever hit our house or one of a family member of a friend, but it could happen. The amount of these are on the increase.....global warming I guess.
I love knowing about these horrible things. I am fascinated so I thought I would copy some stuff so we all are aware of what goes on. Hopefully you will gain a bit of knowledge from this information. I certainly hope none of us is ever faced with one of these. Information copied from howstuffworks.com.
Tornadogenesis is the process and conditions necessary for the formation of tornadoes. The causes of tornadoes are studied by meteorologists who study tornadogenesis. The term refers to the formation of all types of tornadoes, including water spouts, gustnadoes and supercell tornadoes.
Not all thunderstorms create tornadoes and not all tornadoes are created by thunderstorms. But the most common method of violent tornadogenesis stems from a supercell thunderstorm -- one that contains a vortex called a mesocyclone at its core -- which indicates there's a decent chance a tornado is in the works. So, the first few factors on our list are all components needed to build a supercell and, in turn, a tornado -- and the last couple are ones that could contribute to the tornado formation itself.
1. Raindrop Size: New research recently published in Geophysical Research Letters suggests that a storm's spread of raindrop sizes could be an indicator of the likelihood a tornado will form. 3-D study of the microphysical conditions inside a supercell storm.
They studied a number of atmospheric variables and found that large raindrops tend to cluster together more than smaller ones, and are also less prone to evaporation. Since evaporation cools the air (as opposed to the heating that occurs with condensation) this means the air beneath a storm cloud will be warmer than if smaller drops were present -- and we know that warm moist air is just the thing to fuel a massive supercell that spawns tornadoes.
2. Gravity Waves: Once the stage is set for a mesocyclone supercell, another atmospheric occurrence that could up the chances of a twister is a set of incoming gravity waves. Gravity waves are like ocean waves; disturbances in the fluid atmosphere, say powerful gusts of wind or soaring mountain ranges, can cause the air to ripple and roll. Enter the GrITs theory: Gravity wave Interactions with Tornadoes.
3. Moisture and Instability: Another ingredient necessary for tornadogenesis is moisture. As the air begins to rise, its dew point lowers and the moisture cools and condenses to form the storm cloud.
Water vapor releases incredible amounts of heat as it condenses into raindrops, and it's this heat that fuels the storm, revving up a convective cycle of moving air. Thunderstorms are super powerful, and all their energy and furious wind speeds create a positive feedback loop that propagates until the supercell reaches mammoth proportions.
It's also important to note that instability -- the difference between the temperature and moisture levels of air from the bottom to the top of the parcel -- works to intensify a storm.
4. Air Temperature: A second important component needed for supercell formation and tornadogenesis is warm air, especially in relation to parcels of air higher up in the atmosphere. Many, although not all, supercell thunderstorms associated with tornadoes form at the boundary between cold, dry air and warm, moist air.
At the border between these two air masses, the rising warm air helps ignite rotation by fueling the towering updraft that pulls additional warm air up in its wake. The powerful updrafts associated with thunderstorms are aided by uneven heating of the Earth's surface -- one of the reasons they're common in the afternoon hours.
Once warm air reaches the top of the storm, it spills over the backside as a rear flank downdraft and is recycled back into the storm. If the air is too cold, the storm weakens and tornadoes don't form.
5. Wind Shear and Updraft: One characteristic that's generally necessary for a strong supercell -- and subsequent tornado -- is wind shear, a difference in the wind speed at varying altitudes or directions. Air currents are often more powerful at higher altitudes, for example, where jet streams can send them tumbling into a horizontal loop.
As the thunderstorm begins to form, the accompanying updraft can also encourage horizontal spin, but it's this next event that's key -- for a thunderstorm to generate a tornado-spawning mesocyclone, the supercell's powerful updraft must succeed in raising, sustaining and tightening the central vortex at a near vertical alignment.
If this step is reached, powerful forces within the whirling mesocyclone can achieve a balance between the inward and outward flow of air and create what is known as the dynamic pipe effect. The low-pressure center of the vortex (the pipe) sucks additional air up into the storm and lengthens the rotating tube that could potentially become our funnel cloud.
Menard County History of Tornadoes Since 1950.
- 6/16/1973: Brief touchdown on the north edge of Athens. (9:35 pm....magnitude F0)
- 5/9/1995: This tornado had touched down in far northern Sangamon County east of Salisbury. It moved northeast, and clipped a portion of Menard County south of Athens, at the Brookwood Mills subdivision. Here it destroyed 1 home and damaged 13 others. After moving back into Sangamon County, it again entered Menard County south of Fancy Prairie, before continuing into southwest Logan County. Total Menard County damage was $1 million. (4:25pm...magnitude F3) This is the one which destroyed Cantrall Grade School and the Methodist Church.
- 5/12/1998: Brief touchdown in a field 2 miles east of Petersburg. (7:55 pm....magnitude F0)
- 4/8/1999: This tornado first touched down near Sinclair, in northeast Morgan County. It traveled through Ashland, in extreme southeast Cass County, before entering Menard County 4 miles southwest of Tallula. It was on the ground for 1 mile in Menard County. (7:54 pm...magnitude F0)
- 4/2/2006: Brief touchdown in Greenview, causing minor house damage. (5:22 pm....magnitude F0)
- 12/31/2010: This strong tornado touched down on New Year's Eve near Lake Petersburg. (12:37 pm...magnitude EF3)
The last one we had on June 5, 2011 through Sweetwater. It must not have been classified as a tornado. This one I heard and saw the dark cloud going past our house right before I raced to the basement around 7 pm. Menard County officials say it was a tornado...and it did quite a bit of damage.
This utube is of the tornado which destroyed the Cantrall Grade School:
and here's the Illinois Times story on the Cantrall tornado:
Let's hope our area doesn't create any more tornado history anytime soon. But if one comes at least we know how they work.
Thought For The Day
There is always room at the top --
after the investigation.
--Oliver Herford
Please watch out for motorcycles. It's time for motorcycle riders to be out. And, there are already reports of accidents. The funny thing is that people try to justify that most motorcycle wrecks are because the rider in Illinois didn't have a helmet on. Believe me the fact that the rider didn't have a helmet on didn't have a dang thing to do with the cause of the wreck.
Yes, most riders in Illinois don't wear helmets. If you have ever worn a helmet in the hot summer sun, you would know why.....but there is danger and mostly because of other drivers being so discourteous to the motorcyclist. So when you go out.....be sure to watch for a rider....their headlight will always be one so that you can more easily see them ....Watch for them .... and give them room .... and when you pass them, don't cut in front of them too quickly. Believe me I know that drivers are discourteous .....we ride and have been cut off many many times .... drivers cut in front of the motorcyclist quite often and pull out in front of them from side roads. So, what's more dangerous .... discourteous drivers or wearing no helmet? Anytime a motorcyclist rides a bike it's dangerous and most likely a little plastic helmet won't protect them much.....but a vehicle driver giving them room will help their chances of not having a wreck. RANT OVER.
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