National Oceanic and Atmospheric Administration (NOAA) 73

Science | SERVICE | Stewardship UNDERSTAND THE EARTH

Tornado in a Bottle

“And then I was enveloped by the freight train roar...as 

I got to the stairs all of the front of the building blew 

in...like a bomb went off, just a huge explosion behind 

me...And then screaming wind...While I was crouched 

under the desk the building was breathing. You could 

feel the floor lift about a foot and then you could feel it 

drop...I thought any second this is going to drop and 

we are all going down to the first floor with the building 

on top of us. I was terrified when the building started 

moving, I thought I’m gonna die...” 

Bill Morgan

Journalist and retired Police Information Offi cer

recalling the tornado that struck Lubbock, Texas on May 11, 1970, 

killing 26 people and injuring hundreds

Tornadoes cause an average of 70 fatalities 

and 1,500 injuries each year. These numbers 

would be much higher without NOAA’s tornado 

warning and research programs. Nationwide 

tornado forecasts and urgent tornado warnings 

are issued by the National Weather Service 

and broadcast over NOAA’s All Hazards Weather 

Radio network, which is the nation’s one-stop 

source for weather and emergency information. 

NOAA’s National Severe Storms Laboratory is 

a leader in tornado-related research, and in 

developing technologies such as Doppler radar 

to improve forecasts and warnings of tornadoes 

and other severe weather.

When you hear the word “tornado” what picture 

pops into your mind? For most people it is the 

funnel-shaped black cloud, with spiralling 

winds called a “vortex.” Here’s how you can 

create your own “tornado in a bottle.”

What You Will Do

Create a vortex similar to the 

wind pattern of tornados

Did you know:

• The 1970 Lubbock tornado was classifi ed as F-5, 

which is the highest a tornado can be rated

• In a typical year about 1,000 tornados will strike the 

United States

• The strongest tornadoes have rotating winds in 

excess of 250 mph

• Tornadoes can be up to one mile wide and may stay 

on the ground for more than 50 miles. 

• Tornados can occur at any time of the year and have 

occurred in every state in the country

• More tornados strike the central United States than 

any other place in the world; which is why this 

area is nicknamed “tornado alley”

The Dimmitt Tornado, 

South of Dimmitt, Texas

Courtesy NOAA.
noaa.gov

Discover Your World With NOAA

74

What You Will Need

❒ Two empty two-liter plastic soda bottles

❒ Tornado Tube plastic connector (available 

from science museums, science stores, 

novelty stores, scientifi c supply companies, 

etc.) - OR

❒ Metal washer, about one inch diameter 

with a 3/8-inch diameter hole, and plastic 

electrical or duct tape

❒ Dishwashing detergent

❒ (Optional) Food coloring

How to Do It

1. Fill one of the two-liter bottles about 2/3 full 

of water. Add three drops of dish soap and a 

couple of drops of food coloring to help make 

the vortex more visible.

2. Screw the plastic connector onto the bottle 

containing the water, then attach the empty 

bottle to the open end of the connector. Or, 

tape two bottles together with a fl at washer 

between them. Use plastic electrical tape or 

duct tape.

3. Turn the two-bottle assembly over, and place 

the assembly on a table with the fi lled bottle 

on top. Watch the water slowly drip down 

into the lower bottle as air simultaneously 

bubbles up into the top bottle. The fl ow of 

water may come to a complete stop. Now, 

rapidly rotate the bottles in a horizontal 

circle a few times. Observe the formation of a 

funnel shaped vortex as the top bottle drains 

much more quickly. You can make the vortex 

with a single bottle by twirling the bottle and 

holding it over a water basin or the ground 

to drain, but you lose the water and have to 

refi ll the bottle each time you use it. Now you 

know how to use a liquid tornado to quickly 

empty a large bottle!

What’s Happening

When the water is not rotating, surface tension 

creates a skin-like layer of water across the small 

hole in the center of the connector or washer. If 

the top bottle is almost full, the weight of the 

water is suffi cient to push out a bulge in this surface to form a large drop, which then drips into 

the lower bottle. As water drops into the lower 

bottle, the pressure in the lower bottle increases 

washer

vortex
National Oceanic and Atmospheric Administration (NOAA) 75

Science | SERVICE | Stewardship UNDERSTAND THE EARTH

until air bubbles are forced into the upper bottle. 

The pressure of the water’s weight at the surface 

of the connector or washer decreases as the 

water level in the upper bottle drops. When the 

water level and pressure decrease enough, the 

water surface can hold back the water and stop 

the fl ow completely.

When you rotate the bottles in a horizontal circle, the water in the upper bottle starts rotating 

as well. As the water rotates, forces called centripetal forces pull the water toward the center 

of the bottle. At the same time, gravity pulls the 

water toward the drain hole. As the water drains 

into the lower bottle, a vortex forms. As water 

particles at the outside of the bottle move toward 

the hole, the speed of the particles increases and 

the centripetal forces increase. The slope of the 

water shows where centripetal forces are increasing. So at the bottom of the vortex, the slope 

of the water is steeper because the centripetal 

forces are increasing as the water moves with 

higher speeds and in smaller circles. The water 

drains smoothly and rapidly because the hole in 

the vortex allows air from the lower bottle to fl ow 

easily into the upper bottle. 

There are many examples of vortices in nature, 

including whirlpools, hurricanes, the Great Red 

Spot on Jupiter, sunspots, and spiral galaxies 

(such as our own galaxy, the Milky Way). Keep 

in mind that while the spiralling motion makes 

many vortices look similar, they occur for many 

diff erent reasons. The vortex in your “bottle 

tornado” is caused by horizontal spin (provided 

by you) and gravity. But a real tornado in the 

atmosphere is caused by a combination of wind 

shear, changes in atmospheric pressure, and 

centrifugal force.

By the way, tornadoes in the atmosphere happen on a relatively small scale (compared to the 

size of the whole atmosphere). This means that 

tornadoes may rotate clockwise or counterclockwise, regardless of where they are on Earth; just 

like your bottle tornado can be made to rotate in 

either direction.

Oldest known photo 

of a tornado. 

August 28, 1884, 

Howard, South Dakota. 

Courtesy NOAA.

Want to Do More?

Find out more about tornadoes at NOAA’s Tornadoes Web page, http://www.noaa.gov/tornadoes.html. You may also want to visit the Tornado 

Project’s Web site, http://www.tornadoproject.

com/.

Portions of this activity are adapted from an Exploratorium 

Science Snack (http://www.exploratorium.edu/snacks/).

Tune In to NOAA Weather Radio

NOAA Weather Radio (NWR) broadcasts local 

weather forecasts 24 hours a day from local 

offi ces of the National Weather Service. NWR 

is an All-Hazards program that broadcasts 

warnings and information about emergencies 

that include:

• natural events such as tornadoes, hurricanes, 

fl oods, and earthquakes;

• technological accidents such as chemical 

spills, oil spills, nuclear accidents; industrial emergencies, shipping accidents, or 

train derailments;

• AMBER alerts; and

• terrorist attacks 

NWR broadcasts cannot be heard on a simple 

AM/FM radio receiver, but the Weather Band 

is built into many automobile radios, walkie-talkies, marine radios, and other receivers. 

Prices for Weather Radio receivers start at about 

$20. Some receivers have a built in alarm that 

is turned on by a special tone sent from NWR 

during an emergency to signal that information 

is being broadcast about a life-threatening 

situation.

For more information about NOAA Weather Radio, visit http://www.weather.gov/nwr/