See that white spot there in the middle where it says “Greatest Threat?” Oh yeah…that’s right about where I live. At least we aren’t in the overnight area. It may not be considered the greatest threat area, but nighttime tornadoes are more likely to cause casualties, because people are often caught unaware or unprepared.
Now, as I stated in a previous entry, I have a mild fascination with tornadoes. But unless you’re a meteorologist, sometimes the ‘scientific explanations’ can get a little…verbose. So this is the most helpful description of the process that I have seen:
In order to form a tornado, you need three very different types of air to come together in a particular way:
- Near the ground, there’s a layer of warm, humid air and strong south winds. In the upper atmosphere, you’ll find colder air and strong west or southwest winds. The air near the surface is much less dense than the cold, dry air aloft. This condition is called instability. It means that if the warm, moist air can be given an initial push to move upwards, the air will keep on rising, sending moisture and energy to form a tornado’s parent thunderstorm.
- The second ingredient is a change in wind speed and direction with height, called wind shear. This is linked to the eventual development of rotation from which a tornado may form.
- The last thing you need is a layer of hot, dry air between the upper and lower layers. This middle layer acts as a cap and allows the warm air underneath to get even warmer and make the atmosphere even less stable.
When a storm system high in the atmosphere moves east and begins to lift the layers, it begins to build severe thunderstorms that spawn tornadoes. As it lifts it removes the cap, setting the stage for explosive thunderstorms to develop as strong updrafts form. If the rising air encounters wind shear, it may cause the updraft to begin rotating, and a tornado is born.
We’ve already had a t-storm earlier this morning and right now the day is bright, although the sky is still full of clouds. But the window of time today for worst threat of tornadoes is still ahead of us, between roughly 4 to 9pm. I can hear the wind picking up.
I’m anxious, and am trying to plan for a safer place for my family and I to be than this single story building in which my apartment is located. But I am also kind of excited and hoping to get a glimpse firsthand of one of nature’s most interesting weather phenomenon. Fingers crossed for my own pictures…(oh, and that no one drops a house on me, of course.)