Monika Davies - Tornadoes

CONTENTS

WORDS IN THE GLOSSARY APPEAR IN BOLD TYPE THE FIRST TIME THEY ARE USED IN THE TEXT.

DEADLY TWISTERS

Often seen across a dramatic skyline, a tornado is a whirling and twisting dark column of air that leaves mass in its wake. Tornadoes are a common sight in many areas of the United States. These forces of nature can pull up large oak trees from their roots, can destroy entire apartment buildings, and are sometimes responsible for a high number of deaths and injuries.

While tornadoes hit many parts of the world, the United States is where the majority of tornadoes strike. In this book, well examine how tornadoes develop, the different types of tornadoes, and how we can track and prepare for the tornadoes of the future.

A TORNADO CAN LAST FROM BETWEEN A FEW MINUTES TO A FEW HOURS. HOWEVER, MOST TORNADOES TOUCH THE GROUND FOR ONLY ABOUT FIVE MINUTES.

TORNADO FACT FILE

A tornado is a column of fiercely winds that extends from a storm cloud to the ground. In most places in the United States, wind speeds usually dont exceed 15 miles (24 km) per hour. The most powerful tornadoes have winds that reach more than 300 miles (483 km) per hour!

Tornadoes can cause a lot of harm in a community. They rip up trees and knock down buildings. Its important to know how to be safe during a storm like this. First, lets learn how tornadoes form.

EXPLORE MORE

IN 1950, THE NATIONAL WEATHER SERVICE (NWS) BEGAN STUDYING, FORECASTING, AND WARNING THE PUBLIC WHEN A TORNADO MIGHT HIT. THE NWS ISSUES A TORNADO WARNING WHEN A TORNADO IS EXPECTED AND CITIZENS SHOULD LOOK FOR SAFE SHELTER.

A TORNADO WATCH IS ISSUED TO LET CITIZENS KNOW THEIR AREA HAS CONDITIONS THAT COULD CAUSE A TORNADO AND THEY SHOULD BE PREPARED.

FORECAST:

TO MAKE AN INFORMED GUESS ABOUT FUTURE WEATHER

and creates cumulonimbus clouds, which are thick, tall rain clouds. Cooler air moves in below to replace the rising warm air, resulting in wind.

MOST TORNADOES FORM FROM SUPERCELL THUNDERSTORMS. SUPERCELL THUNDERSTORMS ARE THOSE THAT LAST LONGER THAN AN HOUR. THEY GROW FROM A LEANING, SPINNING UPDRAFT THAT CAN BE 10 MILES (16 KM) ACROSS AND 50,000 FEET (15,240 M) TALL!

EXPLORE MORE

NOT ALL SUPERCELL THUNDERSTORMS LEAD TO A TORNADO. IN FACT, ONLY AROUND 20 PERCENT OF SUPERCELL THUNDERSTORMS ACTUALLY CREATE A TORNADO! SCIENTISTS ARE STILL UNSURE WHY THIS IS THE CASE.

SUPERCELL THUNDERSTORM

The storms strength gathers as the cloud mass grows. Water droplets in the clouds have electrical charges that create lightning and the accompanying thunder. When wind speed increases and wind direction changes, a tornado may form.

ALTHOUGH A SUPERCELL THUNDERSTORM IS THE LEAST COMMON TYPE OF THUNDERSTORM, IT IS THE MOST DANGEROUS TYPE.

U.S. TORNADO DATABASE

Tornadoes have happened on every continent except Antarctica. By far, the United States is the country with the most tornadoes every year. Each year, around 1,253 tornadoes occur in the United States. The tornadoes in the United States are also the strongest and most destructive in the world. Tornadoes have occurred in every U.S. state. Theyre found in the greatest number and strength in the central part of the country, which is nicknamed Tornado Alley for this reason. This area includes parts of Texas, Oklahoma, Kansas, Nebraska, South Dakota, and Colorado.

THE UNITED STATES HAS THE WORLDS LARGEST NUMBER OF TORNADOES EVERY YEAR. THE NEXT COUNTRY TO EXPERIENCE A HIGH NUMBER OF TORNADOES IS CANADA, WHICH HAS AROUND 100 TORNADOES EVERY YEAR.

DESTRUCTIVE:

CAUSING SOMETHING TO BE DESTROYED OR RUINED

. This huge area of rotating aircalled a mesocyclonecan be from 2 to 6 miles (3 to 10 km) wide. Within this area, marked by a mass of low-lying clouds called a wall cloud, tornadoes form.

STORM CHASERS

The 1996 movie Twister was about scientists who chase tornadoes to study them. Storm chasers dont just exist in movies. There are real-life storm chasers who put themselves in danger! Some are scientists who want to learn more about how weather happens. Some are photographers who want to take pictures of storm scenes as they happen. However, real-life storm chasers are usually experts who have training. They understand storm conditions, as well as the dangers and risks of chasing a storm. Storm chasers can drive around looking for a tornado for 12 hours or more! Storm chasing often involves a lot of waiting time too.