Text Leveling System

Tornadoes!

RDQ:	1010	Max Word/Sent	34	Total Words	1667		Diff Words	582
Lex	740	Ave Word/.Sent	9	Hi Freq occurs	1000	60%	Hi freq	205	35.2%
AR	3.6	Long Sentences	4	Low Freq occurs	72	4.3%	Low freq	45	7.7%

The air was hot, sticky and still. A good sign. Dark thunderclouds crackled over the road ahead. Even better. Scientist tim Marshall and his friend Roy Britt knew they were close. But they weren't sure how close. Then it happened. A spinning funnel of wind dropped from the sky. Less than a mile away, it smacked the ground. Hard. The giant funnel was white and almost noiseless. It kicked up clouds of dust, branches, and bits of unknown objects. That's it! Tim thought. It was what he had hoped for - a tornado! Tim and Roy are tornado chasers. They film and study tornadoes. Tim and Roy must drive very close to the deadly storms. On that spring day, they almost came too close. Tim parked the van southeast of the tornado. That's usually the safest spot for filming. The reason is that tornadoes normally travel from the southwest to the northeast. Then the two tornado chasers set up their tools: video cameras, tripods, and a TV for watching weather reports. Tim and Roy watched the tornado twist across the Texas plain. They felt safe. The tornado was moving away from them. They filmed the action. Then the tornado changed direction. It made a big, choppy circle. It was heading toward Tim and Roy! The tornado was now chasing them, instead of the other way around! Tim and Roy quickly tossed everything into the van. They jumped in and sped away. Tornadoes usually travel about 30-50 miles per hour. That is under the highway speed limit. But some tornadoes go 70 miles per hour. That's way too fast to outrun - even in a van! If the tornado did catch Tim and Roy, the winds could pick up the van and throw it like a deadly missile. To avoid the tornado, Tim and Roy had to drive into a hailstorm. Chunks of ice as big as softballs cracked the windshield. The van rocked and rolled in 60-mile-per-hour winds. But the deadly tornado missed them. It crossed the road just behind them. It ripped some trees right out of the ground. Then the funnel lifted up and out of sight in a wall of rain. Tornadoes are the most powerful storms on Earth for their size. These mighty storms are tall, skinny funnels of spinning air. The funnels stretch from the ground to mountain high clouds - about 15,000 to 20,000 feet! Their winds are among the fastest on Earth. They can blow up to 300 miles per hour, which is almost as fast as a D C-10 jet. The world's fastest winds can cause some of the world's worst damage. In 1890, a tornado in Massachusetts blew away roofs and walls of houses. But the furniture inside was just fine! In 1928, a tornado in Kansas plucked the feathers right off some chickens! In 1931, a tornado in Missouri lifted an 83-ton train ... and tossed it 80 feet off the track! In 1948, a tornado in Iowa flipped a house upside down. but the house stayed together! In 1991, a tornado in Missouri tore up a patch of lawn - the grass and roots! It left behind only smooth mud! The United States gets more tornadoes than any other country - an average of 800 tornadoes every year. Every year, dozens of Americans die from these tornadoes. Tornado chasers study tornadoes close up. That way, they can tell when and where the next tornado may form. This helps weather experts warn people to take cover. Some chasers, like Tim and Roy, work by themselves. Others are part of a team of experts at the National Severe Storms Laboratory in Norman, Oklahoma. The lab is in the heart of Tornado Alley. This is an area, from Texas to the Dakotas, where more than half of all U.S. tornadoes touch down. Each spring, hundreds of tornado chasers go to Tornado Alley. Most tornadoes take place in April, May, and June. Texas, Oklahoma, and Kansas are the hardest hit states. But a tornado could form in any month, in any state. Tornado chasers don't wait for a tornado to hit and then go try to find it. The tornado would be long gone. Most only last minutes or even seconds. Also, tornadoes may be tall, but they're usually skinny. Some can be very skinny. A tornado might wreck on house and never even touch the house next door! They are so fast and skinny that Tim Marshall catches a tornado only one out of every 10 chases! It takes a lot of planning to find a tornado. Most tornadoes form in the afternoon. But Tim goes to work early in the morning. He needs time to study the weather. He has to map out a chase route. And he has to get there. He may drive hundreds of miles from his Texas home during a single chase! First Tim calls the National Severe Storms Forecast Center. He asks for information about the weather.Tornadoes form inside huge thunderstorms. These storms can span several states. Tim wants to know if any storms are in the area. So he checks with the radar experts at the Storm Center. Radar tracks thunderstorms as they move. The storms show up on a radar screen as blobs of color. The chasers hope one of those blobs has a hook pattern like an S or a 6. That stands for a funnel cloud - and funnel clouds can become tornadoes! The most likely spot for a tornado is along a storm front. That's where a large mass of cold air meets a large mass of warm air. This is how a funnel cloud forms in Tornado Alley. Cold, dry air blows in from the west. It sits high in the air. Colder, higher air may blow in from the north. Meanwhile, warm, wet air blows in from the south. This air is low to the ground. Normally, warm air rises. But when a double blanket of cold air sits on warm air, the warm air can't rise. The cold air is blocking it. The cold air can't drop, as it normally does. The warm air is in the way. So the masses of air slide, twirl, and push against each other. They make crazy-shaped clouds and strong winds. Finally, some warm air may punch a hole up into the cold air. It looks like a giant mushroom cloud. This rising warm, wet air cools. Rain or hail begins to fall. Then the cloud may start to spin, like water going down a drain. this spinning cloud is called a funnel cloud. On the radar screen at the Storm Center, the funnel cloud looks hook-shaped. The Storm Center sends out a tornado watch. This is a message that tells everyone in the watch area to take cover in case a tornado touches down. Everyone, that is, except the tornado chasers. They get into their cars, vans, jeeps, and trucks. And they drive off to meet the brewing funnel head-on! They watch and film the funnel cloud. As the winds get faster, the cloud spins in tighter and tighter circles. About half the time, a funnel cloud breaks up and disappears. But at other times, a funnel cloud drops down from the sky and touches the ground. Touching down turns a funnel cloud into a tornado. Some people in Tornado Alley call it a twister. Every tornado, or twister, has its own color, sound, and shape. And each twister behaves differently. Usually, a tornado's color matches the color of the ground. Reddish dirt makes a red tornado. Some tornadoes are white. Others may be gray or brown. Tornadoes can sound like a hundred jets taking off ... or a thousand roaring trains ... or a million buzzing bees! But some tornadoes, like the ones on the open plains, make very little noise. The sounds are caused by objects that the tornadoes hit or pick up and carry. A tornado's shape may be its strangest feature. People describe tornadoes in many different ways. Someone said one tornado looked like the trunk of a giant elephant. It sucked up water, dirt, trees - everything in its path. Then it rose into the sky and disappeared. People have said that tornadoes have looked like barbershop poles, hourglasses, wobbly spinning tops, slithering snakes, and even a giant lawnmower1 This twister ""mowed"" down a strip of trees in a forest. Tornadoes also do different kinds of damage. A weak tornado might blow off the roof of a house but leave the walls standing. A stronger tornado can splinter a house to pieces. Only a bathroom or inside closet may be left standing. Super strong tornadoes can send pieces of wood sailing through the air, only to land like porcupine quills in a mattress! If a tornado can wreck a house, imagine what it can do to a tornado chaser. Luckily, so far, no chasers have been directly hit by a tornado. Many, though, have come close. Tornado chasing has other dangers, too. One danger is lightning. Lightning occurs in all the thunderstorms. The electric bolts usually hit the tallest object in an area. On the open plain, the tallest object is often a human. In 1983, lightning struck right next to five tornado chasers. Luckily, they all lived. Car accidents are another danger. Tornado chasers have also been hurt in car crashes. Sometimes, they were driving and sky-watching at the same time. Other times, they got hit by cars that were fleeing the same storm they were chasing. Hail is a danger, too. The falling chunks of ice can hit hard enough to break windows and dent cars. ""Usually, if we stay in the car, the car gets pounded, but we don't,"" said Tim. So why do these scientists risk their lives? They do it to save the lives of others. The number of tornado-related deaths has dropped in recent years. One reason is that tornado chasers have helped the Storm Center warn people faster. ""Tornadoes are hard to predict,"" said Tim. ""They're dangerous. But they're very, very exciting.""

Subjective Criteria

Illustrations: Little support

Vocabulary: Some difficult words

Language: Many descriptive words

Sentences: Some Long/Complex

Text structure: Story/Poem

Inferences: Several Implications

Complexity: Several ideas - closely related

Chapters

Features

Character traits

Clear cause/effect

Topic

*Weather

Wind

Danger

Nature

Tornadoes

Low Frequency Words

average	brewing	chasing	filmed	filming
funnel	hailstorm	laboratory	lawnmower	likely
luckily	marshall	massachusetts	masses	mattress
meanwhile	missile	missouri	mowed	mushroom
national	northeast	object	objects	occurs
plains	plucked	radar	recent	reddish
related	route	scientist	severe	slithering
smacked	southeast	southwest	thunderstorms	tornado
tornadoes	unknown	warn	windshield	wobbly