Lesson 6: Rock and Roll Weather
(Tornadoes, Hurricanes, Lightning)

We have all seen images or been a part of some type of violent weather. During the spring and early summer, tornadoes can rip across the state. Thunderstorms can bring strong winds, hail, and lightning. Though we don't directly experience hurricanes, reports of the damage they cause along coastlines are amazing.

Lightning is electricity. It is thought to be caused by the friction of air moving in different directions. A stroke of lightning can move from cloud to cloud or from ground to cloud. The path of lightning from ground to cloud is made by a leader stroke, which goes from the bottom of the cloud to the ground.

Lightning heats the air in the path of the stroke to above 45000°F, creating a shock wave. This wave disintegrates within a few feet of the stroke, leaving sound waves that make thunder. The rumbling sound from thunder comes from sound waves travelling different distances and from bouncing off of clouds. A lightning bolt may be several thousand feet long. The sound from the part of the bolt closest to you will reach your ears before the sound from the farthest part of the bolt.

When a thunderstorm approaches, do not stay outdoors. Lightning can occur even when a storm may look like it's a long way from where you are. Do not go near trees – many people are hurt or killed when they take shelter under a tree, and lightning hits the tree. If you are out in the open and cannot get indoors, try to stay as low as possible and away from tall objects that may conduct electricity.

The word tornado comes from the Spanish word tronada, or thunderstorm. Tornadoes consist of a very rapidly rotating air column, which may contain wind speeds of 100 to over 300 miles per hour. Most are at the low end of this speed. The entire tornado will move across the ground at 20 to 40 miles per hour, and most last less than 30 minutes. The width of a tornado is usually not much larger than the size of a football field, but in some rare cases can be almost a mile in width.

Tornadoes can do strange things. In March 1925, Howard Rawlinson watched as a tornado turned into two funnels. One hit a barn and picked it up. After the tornado was gone, a live chicken was found in a rolled up ball of barbed wire, still alive, but plucked clean.

To rate how severe a tornado is, a scale called the Fujita-Pearson scale is used and is shown below.

Hurricanes form over warm oceans, slightly north or south of the equator.

Hurricanes are large storms, some being over 300 miles in width. Wind speeds can rage from 75 to almost 200 miles per hour. Hurricanes are slow movers, sometimes staying almost stationary for a day or more.

Naming hurricanes comes from a list made several years in advance. Hurricanes were given names so they would be easier to individualize. Alternating male and female names are used. Names are also associated with letters of the alphabet, like, Andy, Betty, Clark, and Donna.

Activity One – Hail, Hail, The Bad Weather's Here!

Materials: Paper, pen/pencil, encyclopedias, or computer

Setting Up the Activity: Write a one-page report on one type of extreme weather, such as tornadoes, hurricanes, lightning, hail, blizzards, or floods. Discuss how the topic selected affects Illinois.

Activity Two – Tornadoes on Film

Materials: Video player/monitor, Any video or film showing tornadoes.

Setting Up the Activity: Watch the video, then have a class discussion on student's experiences with tornadoes—whether they have seen a funnel cloud or been close to or actually in a tornado.

Discuss the difference between a tornado watch and a tornado warning. A tornado watch means conditions are favorable for a tornado, but no tornado has been seen. A tornado warning means a tornado has been found on weather radar or actually seen by someone.

Some things to remember if a tornado warning occurs for your area:

• Listen to weather radio or watch your local TV station for updates.
  
• Go to an inside wall on the lowest floor.
  
• When in school, stay away from rooms with wide roofs that could collapse easily, such as gyms or auditoriums.
  
• Keep disaster supplies available, such as flashlights, candles, matches, and a first aid kit.