Tornadoes are a force of nature and still something of a mystery. We know that they are rotating clouds that extend between a thunderstorm and the ground in a funnel shape. We also know that the most powerful storms produce wind speeds of 300 miles-per-hour or more. 

But what causes tornadoes? And why don’t they occur in every single thunderstorm?

While we don’t know everything about why tornadoes form, we do know what they look like, the potential damage they can cause, and how to avoid them.

Keep reading for the ultimate guide to the different types of tornadoes.

Tornado Basics: What is a Tornado?

tornado weather storm in the road

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Tornadoes occur when a warm front of air meets a cold front and causes a thunderstorm. These thunderstorms have the potential to produce tornadoes (colloquially called twisters). Rotating thunderstorms best predict tornado activity. We’ll go into how tornadoes form later in the guide.

Tornadoes can occur anywhere or anytime a thunderstorm strikes. However, they are more likely to occur in the Great Plains region of the United States. The plains is a flat strip of land running from North Dakota in the north to western Texas in the south. Why the Great Plains? It is here that the warm air from the Gulf of Mexico meets the cold, polar air from Northern Canada.

The meeting of warm and cold fronts produces more severe thunderstorms and thus statistically more tornadoes.

The Different Types of Tornados

Popular media would leave you to believe that tornadoes all appear like something out of the film “Twister.” But these funnels of destruction actually appear in several shapes and sizes. Some are more destructive than others, and some take on a form that seems to be a tornado but doesn’t technically meet the criteria.

Most of the tornado names listed below are storm observers’ slang used as a way to characterize what they look like. There aren’t precise specifications that place these tornadoes within each category.

Wedge Tornadoes

Meteorologists and storm observers call tornados that are as wide as they are tall “wedge tornadoes,” but the term doesn’t offer any scientific meaning. Wedge refers to the size and shape

These tornadoes tend to be very violent, often EF4 or EF5. However, not all wedge tornadoes cause such devastation. The size of a storm doesn’t indicate the damage it will leave behind.

Cone Tornadoes

When you think of a tornado, you probably think of a cone tornado. It is the kind of twister that features a broader base (near the clouds) and becomes narrower as the funnel reaches for the ground.

Stovepipe Tornadoes

Stovepipe tornadoes are very similar to cone tornadoes, but these storms keep a tall and narrow cloud base that does not vary much between the cloud base and the ground. In other words, it takes on the shape of a stovepipe.

Rain-Wrapped Tornadoes

Rain-wrapped tornados are a less common type of storm, and they are particularly dangerous because the storm hides behind a curtain of intense rainfall. In some cases, the only indication of the twister comes from the radar.

Multi-Vortex Tornado

A multi-vortex tornado is like the three-headed hydra of storms. The name gives it away: the tornado features two or more vortices rotating around a central, larger tornado. You won’t always see the vortices with the naked eye because as the wind picks up debris, the vortices become obscured.

Often, storm watchers identify the tornado through the damage left on its path. These tornados tend to cause small areas of extreme damage.

Rope Tornado

A rope tornado is a tornado at the ends of its cycle. These look long and narrow, like mariner’s rope, and look as though the storm is beginning to dissipate. However, rope tornadoes not only continue to wreak havoc on the ground but once it disappears, the wind can produce a new area of rotation and form a brand new tornado.

How Tornadoes Form

Both supercell and non-supercell thunderstorms produce tornadoes. The most common—and most dangerous—tornadoes come from the aptly named supercell storms.

You only see tornadoes when a thunderstorm produces an exact combination of winds.

When the air rises in a thunderstorm, and it meets winds blowing in different directions, then the air can begin to spin. The spinning doesn’t happen immediately; the winds jostle it as it rises.

The air can meet diverging winds in a thunderstorm and begin to spin without creating a tornado. The spinning air needs to occur not only towards the top but also towards the ground to transform into a tornado.

Why would the air spin near the ground? When the air in the thunderstorm sinks to the ground, it spreads out across the land and creates gusts of wind. When the air is warm, the gusts rise as they blow — the cooler air sinks. With rising and sinking gusts at ground level, it can begin to spin.

As the spinning air over the ground begins to pick up speed, it is also drawn inward towards an axis through a physical reaction called the conservation of angular momentum. If the rotating air near the ground doesn’t spin fast enough, then it won’t generate a tornado.

Often tornadoes occur between three o’clock in the afternoon and nine o’clock in the evening. As mentioned, they predominantly impact the Plains and Midwestern states with Texas, Oklahoma, and Kansas see both the greatest number and the most severe storms each season.

Tornadoes season in the south reaches its peak between March and May, but June through August are the primary months for tornadoes in the northern states.

However, tornadoes can occur at any time when there is a thunderstorm.

Why Are Tornadoes So Unpredictable?

Tornadoes come almost exclusively from supercell thunderstorms. But why do we have so few tornadoes compared to storms?

Scientists don’t yet know why one thunderstorm produces a tornado when another doesn’t.

One belief is that you need high relative humidity and strong wind changes. However, these make no difference if the downdraft isn’t placed exactly in the right part of the storm.

Harold Brooks, who works as a research meteorologist at the National Severe Storms Laboratory (NSSL) and the National Oceanic and Atmospheric Administration (NOAA), says it’s easiest to understand the process through the story of Goldilocks.

Like Goldilocks, there needs to be the perfect mix of wind and air—not too hot, not too cold, not too high, and not too low. It all needs to be just right.

How Do Scientists Classify Tornadoes?

You may have heard of F2 or F5 tornadoes. The “F” stands for the Fujita scale, which represents the old way of classifying the strength of a storm.

Today, meteorologists and scientists at the National Weather Service use the enhanced Fujita scale (EF), which they unveiled in 2007.

The Enhanced Fujita Scale is a scale that represents damage and wind speeds. The scale works as follows:

  • EF0: 65-85 mph, minor damage
  • EF1: 86-110 mph, moderate damage
  • EF2: 111-135 mph, considerable damage
  • EF3: 136-165 mph, severe damage
  • EF4: 166-200 mph, devastating damage
  • EF5: greater than 200 mph, incredible damage

Minor damage may include some damage to siding or gutters, toppled shallow-rooted trees, and confirmed tornadoes with no reports of structural damage. An EF5 with incredible damage may level well-built houses by ripping them off their frames and throw vehicles and trains as far as one mile.

The scale also includes 28 damage indicators, which represent the degree of damage in ascending order.

Are You Prepared for Tornadoes?

If you live in an area prone to tornadoes, then you need to be tornado-ready. Remember that tornadoes can be unpredictable in almost every way, and the best way to prepare for one is to be ready for even the worst damage.

Creating a Tornado Safety Plan

Do you know where you will go in the event of a tornado? Identifying safe spaces to hide is the first step to tornado preparedness.

You should have a safe space identified in your house, at work, and in places that you spend a lot of time (like the homes of friends and family). Ideally, you all have a basement or storm cellar available to you. But in areas where tornadoes are less frequent, you may find that there is no reinforced underground space available to you.

If you don’t have a basement or cellar, then your next best option is an interior room on the ground floor of your home. The room should be windowless, which often means you choose a closet or bathroom.

Tornado Safety for Kids

If you have school-age children, you have a few extra steps to complete.

If you don’t already, learn about your school’s emergency dismissal policy. Do they send children home during a tornado warning? Where do the children go? Most schools and daycare centers in areas prone to tornadoes have basements and storm-safe areas where children gather in the event of a storm.

In some cases, you may need to nominate a home near the school to send your child to in the event of a storm. You may also need to list an emergency contact if a storm cuts you off from the school.

Your Tornado Safety Checklist

You should always prepare for the worst in the event of a tornado. Circumstances change quickly, and it only requires one downed powerline or tree to leave you cut off from the world.

To protect yourself and your family, you need an emergency supply of food. Set aside three gallons of water per person in your household to prevent dehydration. You should also set aside a three-day supply of food—dried or canned—per person. Be sure to choose food that doesn’t require cooking, and always include a manual can opener.

Although most governments and disaster agencies recommend dried and canned food, don’t feel you are limited to this. If you have (or are happy to buy) a small camping stove, you can provide hot meals with little effort. Just make sure you have enough cooking gas stored.

If you have an infant or baby under two, make sure you have enough formula and baby food to last for three days.

In addition to food and water, you should also store a flashlight and radio. Battery-powered works best (compared to solar powered), and don’t forget to keep extra batteries on hand.

You should also have access to any essential prescription medications. You don’t need to store these, but it is helpful to keep them all in one place and in a plastic tub or bag to fetch them easily as you head for shelter.

Finally, a first-aid kit is critical. Make sure it is fully-stocked and replace any missing or used items whenever you use them. It is also essential to make sure you know how to use the items in the kit.

Removing Debris

Most injuries and fatalities result from the impact of wind-borne or falling debris. Although you’ll be in a shelter, providing the tornado with less debris to pick up better protects your property.

Before tornado season, it’s a good idea to trim your trees. Removing damaged and diseased limbs will stop them from breaking off during storms. You can also make your trees more wind resistant by selectively removing branches that allow the wind to blow through without severing weak limbs.

You should also pick up any items or debris in your yard. Felled branches, in particular, turn into missiles in high-speed winds. Any toys or yard decorations could also easily disappear in the wind.

Preparing for Insurance Claims

Keep all your essential documents (birth certificates, passports, etc.) in 

If you live in an area prone to tornadoes, it’s a good idea to keep an inventory of your home and the valuable items in it with your important documents. Supplement the list with the approximate value of the items as well as photos. 

Your inventory will make any home insurance claims far simpler.

Tornadoes and Fires

Most of the time, we think of the wind destruction associated with tornadoes. While the wind damage can be the most severe part of the storm, it can also be only the beginning. Fires are common after wind events because these storms break gas lines and fell power lines.

When moving around after a tornado, keep an eye out for damaged lines and immediately call your utility company.

Caring for Pets and Animals

Don’t wait until you see the tornado to corral your pets and animals. If they aren’t in the house or barn, get them ready as soon as the tornado watch becomes a tornado warning.

You should also consider preparing an emergency kit for your pets. That means ensuring you store enough food and water for them as well as the human members of your family.

After a Tornado

Don’t wait until you see the tornado to corral your pets and animals. If they aren’t in the house or barn, get them ready as soon as the tornado watch becomes a tornado warning.

You should also consider preparing an emergency kit for your pets. That means ensuring you store enough food and water for them as well as the human members of your family.

Tornadoes Are Incredible – Stay Out of Their Way

Tornadoes can occur in any thunderstorm, and they are incredibly difficult to predict. You also never know which of the types of tornadoes will hit, and the size of the storm is no indication of the danger.

Whether you live in Tornado Alley or you only experience them once a decade, the best way to understand and prepare for tornadoes is always to be prepared. Never underestimate the power and severity of these storms, and follow the instructions provided by the National Weather Service and local authorities.