Tornadoes

A rotating column of air usually accompanied by a funnel-shaped downward extension of a cumulonimbus cloud.

• Cumulonibus Cloud: This cloud, which is part of a larger storm system, is the host of the tornado because the funnel descends from it to create the tornado.
• Funnel Cloud: As the tornado begins, this descends out of the cumulonimbus cloud and broadens at the ends to do the destruction. The wind speeds in this low-pressure core are very low.
• Winds: The winds of a tornado rotate upward in a spiral, causing the tornado to usually rotate in a counterclockwise direction. The further towards the center they are, the faster the winds spin.
• Spiral Updraft: This is the "skin" of air that travels into the parent cumulonimbus cloud from the tornado.
• Inflow: The tornado causes low pressure, bringing the surrounding air in at high speeds to equalize the imbalance. This spiral inflow can reach 110 miles per hour (180 kilometers per hour).
• Suction Vortices: Rotating around the interior of the main funnel, these suctions can be extremely dangerous because of their power.
• Debris: The tornado lifts its destruction to great heights before releasing it, so there is always a cloud of debris at the base of the tornado. This gives some color to the funnel because of everything swirling around it.

Explanation

Tornadoes are cyclones, and therefore they are formed at a front. This is the meeting point of two air masses blowing in opposite directions, and if an updraft of warm air rises up to meet this front, it can set the opposite winds whirling. Tornadoes are born as a whirling formation at the base of a thundercloud. This portion of the cloud begins to drop lower, and the dust and debris circle on the ground directly beneath the cloud. The winds feed their energy into the whirlwind, and soon the funnel becomes visible and broadens into a cone with the wider end in the air. Then, it may broaden at the bottom to produce a cylinder of wind. As the tornado weakens, the funnel narrows again. Weak tornadoes may die before actually forming funnels, or soon afterwards. Tornadoes are extremely loud, with sounds ranging from whistling to a roar like a jet plane liftoff. If the tornado survives, it goes on to do its destructive work until it finally weakens.

What You'll Need:

• two plastic 2-liter soft-drink bottles
• duct tape
• scissors
• pencil
• paper towels
• ruler

Directions:

1. Fill one of the bottles half full with water.
2. Cut a strip of tape about 1 inch by 2 inches.
3. Use the strip of tape to cover the mouth of the bottle with the water.
4. Using the pencil, punch a hole slightly larger than the pencil in the center of the tape.
5. Smooth the edges of the tape around the hole with your fingers, and use tape to secure it.
6. Turn the second bottle over and line up the mouths of the two bottles.
7. Use a paper towel to dry any moisture from the necks of the bottles.
8. Wrap strips of tape around the necks of the bottles to secure them tightly.
9. Flip the bottles so the bottle with the water is on top.
10. Hold the bottles around the necks and quickly swirl them in circles parallel to the floor. (Towards you, to the right, out, to the left, etc.)
11. Set the bottles on a table, with the empty one on the bottom.

What's Happening?

The water is swirling in a funnel shape as it pours through the small hole in the same way the tail of a wind tornado spirals. The water movement occurs due to the action of several forces, just like a tornado. Tornadoes can be seen because the large amount of liquid water in the cloud blocks the light like a thundercloud. The debris picked up from the ground adds color to the swirling wind of the funnel cloud. Read the explanation above to learn more about the formation of a tornado.

Tornadoes are extremely dangerous, and the strong winds can create a lot of damage. Since winds can get to over 150 miles per hour, they can lift large objects, such as automobiles. Surface debris whirls through the air at a high speed and comes down outside the tornado's path. The strong winds cause a lot of damage, and so does the central low pressure that creates the winds. This area can cause a tightly sealed building to explode outward.

Tornadoes can be classified into six categories based on their wind speeds. Below is the table established by Ted Fujita.

The central United States gets the most tornadoes in all of the world. Warm, moist air from the Gulf of Mexico is met by dry air from the West or Southwest in this area. The region of greatest threat goes from western and central Texas up through Oklahoma, Kansas, Nebraska, and Iowa, and eastward through Arkansas, Missouri, Illinois, and Indiana. This area is known as Tornado Alley, and includes the southern and central Great Plains, the middle Mississippi Valley, and part of the Midwest and lower Great Lakes region. The land in this region is gently rolling hills, valleys, and plains. The further you get from Tornado Alley, the less the frequency in the United States. However, Florida has a great amount of tornadoes storming through there. Northern India has some severe tornadoes before and after the summer monsoons, and tornadoes also touch down sometimes in Australia, New Zealand, Japan, Western Europe, Uruguay, and Argentina. But nobody has more tornadoes than the central United States.

It is important to be safe and get shelter when a tornado is headed your way. When possible, head to a sturdy building or a basement. Seek shelter on the lowest floor you can find. A closet or a bathroom is good protection. It used to be recommended to seek shelter in the side or corner of a building farthest away from the approach of the tornado, usually the southwest side, but research shows that damage isn't any less severe on that side than other places in the building. Now the center is suggested as a good place for protection.

Basically, put as many walls between you and the storm. Also, stay away from all windows. If you are caught outside, look for a ditch or depression that won't make rushing rainwater a problem. Crouch under and cover your head and neck with your arms. Be alert to warnings, and seek shelter right away. For more information on how to protect yourself, check out some resource centers near you, or do a search on the Internet.

These are the same formations as tornadoes, but they form over seas and lakes instead of land. Just like tornadoes, they form from cumulonimbus clouds and are extremely dangerous. They up water, mist, and spray in a whirling column, and can build up to several hundred feet high.

In 1952, the U.S. Weather Bureau established a severe-local-storm forecast unit in Washington, D.C. They then moved to Kansas City, Missouri, a tornado prone area, and are still there today. This group is responsible for issuing tornado and severe-thunderstorm forecasts for the entire United States.

Meteorologists have refined their forecasting techniques, but still use basic ideas established in the 1950s. The following is what they look to when they're forecasting:

• The atmosphere is very unstable, and there is relatively warm air near the surface and colder air aloft.
• The lower 5,000 to 6,000 feet of the atmosphere is very moist. There may also be dry air at mid-levels between 9,000 and 14,000 feet.
• High winds associated with the jet stream in the mid and upper atmosphere are over the threat area.
• Since a trigger is necessary to start a rising column of air. They look for certain mechanisms. A cold air mass from the north or northwest converging with the warm, moist air of the frontal boundary. Or perhaps a stream of hot, dry air from the west or southwest is pushing into the warm, moist air.

When a tornado may be developing, the National Severe Storms Forecast Center issues a tornado watch for six to eight hours. An announcement is made over radio and television shortly before the first activity is expected. This warning alerts citizens and encourages them to keep listening for more information. A tornado watch may cover between 15,000 and 25,000 square miles, and most forecasts are followed by confirmations of at least a few touching down in this area. Still, since the area of the watch is so large, the chances aren't too great that an individual will see a tornado.

The local National Weather Service office issues a warning when a tornado has been sighted or is likely to hit a small area, such as a county. This warning is directed toward the people in a smaller region, and is usually only in effect for forty-five minutes or so.

Recently, the National Weather Service installed a Doppler-radar network that senses precipitation and cloud-water targets, and can often spot a yet-unborn tornado within the cloud. Therefore, there are fewer false alarms and many accurate predictions.