Funnel clouds have been observed on every continent except Antarctica. The United States has significantly more than the rest of the world because of low-lying geography and a climate that breeds strong thunderstorms. With wind speeds up to 320 miles per hour, tornadoes kill about 60 people every year in the United States when uprooted trees and debris turn into deadly missiles. Check out our list of tornado safety tips to get prepared!
Beware of fire hazards.
Never strike a match until you're sure you haven't had a gas leak. Anything that holds gas can rupture and be vulnerable to explosions if you see (or smell) leakage after a storm. If you think there might be a gas leak, open all doors and get out of the house. Also watch out for severed electrical wires, which can spark debris piles. Check appliances to see if they are emitting smoke or sparks.
What to do when the storm has passed.
Treat injuries with your first-aid kit, but don't attempt to move anyone who is severely injured. Use the phone only for emergencies, such as calling for an ambulance. Then, listen to the radio for emergency information. If the building you are in is damaged, beware of broken glass and downed power lines as you evacuate. Check on neighbors who might need assistance, but otherwise stay out of the way so that emergency crews can do their work.
What if you're outdoors?
Finding a building is your best bet, but if there's no time, follow the same instructions in the next step.
What if you're in a vehicle?
Never try to outrun a tornado. Get out of your vehicle and try to get inside a building. If there isn't time, lie down flat in a ditch or any low-lying area away from the vehicle. (Hiding below an underpass isn't safe because you're still exposed to flying debris.) Use your hands and arms to protect your head.
What if you're in a public building?
The first choice is always a basement or lower level. If that isn't an option, avoid wide-open spaces such as cafeterias or auditoriums -- there's just not enough physical support for you there. Look for an inside hallway, or a small closet or bathroom (with no windows).
Mobile home residents need to take extra precautions.
If you live in a mobile home, never try to ride out a severe thunderstorm at home; go to a prearranged shelter. As a last resort, go outside and lie flat on the ground using your hands and arms to protect your head. It might be hard to believe that you're safer outside, but since your mobile home isn't built into the ground, it can be picked up and turned into an airborne missile.
Get in position
Once you're in your shelter, find a sturdy piece of furniture, such as a workbench or table, and stay under it. Curl into a ball on the floor, and lock your hands behind your head to protect it from flying debris. If you can't find a table to get under, crouch under a door frame because the beams will offer some protection.
Don't bother opening windows.
It's true that air pressure equalizes when there's an opening in the building, but the American Red Cross says that it's far more important to get to safety than to open windows. If there's flying debris, the windows will most likely break on their own!
Stay away from windows.
At 320 miles per hour, shards of glass can be deadly. You can eliminate this risk if you make sure your shelter area is free of windows. If this isn't possible, protect yourself with a heavy blanket.
Know the difference between a "watch" and a "warning."
There's a big difference in the danger level between the two terms used during stormy weather. A watch simply means that conditions are favorable for a tornado to develop. Be alert, but you don't need to take shelter. If there's a warning, a tornado has been spotted. When a warning is posted for your area, take shelter immediately.
Know how your community sends its warnings.
If it's a siren, stay inside and take cover. Know where the designated shelters are in the buildings where you and your family spend time.
Make an inventory of your possessions.
For insurance purposes, videotape or photograph everything you would need to replace in case you lose it all. When you're sure that you've included everything, keep the inventory somewhere away from the premises, such as a safe-deposit box.
Prepare an emergency supply kit.
Experts recommend that each person (and pet) has supplies for at least three days, including bottled water (two quarts per person, per day), nonperishable food, and a first-aid kit that includes prescription items as well as aspirin and antacids. Make sure you have tools such as a can opener, utility knife, wrench (for turning power valves), whistle, battery-powered radio, several flashlights, and batteries. Each person will need blankets, clothing, rain gear, and heavy-soled shoes or boots. Lastly, stash away some cash and a copy of credit cards, passports, social security cards, phone numbers, and insurance information. Once a year, check your supplies and determine if family needs have changed.
Conduct tornado safety drills with your family.
Make learning quick and fun, and children will remember the basics of what to do, especially if you go through the motions several times. Just as most kids know what to do if their clothes are on fire, the same drill could be applied for tornado safety -- instead of "Stop, drop, and roll" try "Run, duck, and cover!"
Determine the best locations for shelter at home and work.
The safest location is always a basement, below the deadly wind and projectile objects. If you can't go underground, find a small interior room or hallway on the lowest level of the building.
These massive clouds form when wildfires give off heat. HowStuffWorks looks at how climate change is making conditions favorable for more to form.