This entry is part 3 of 3 in the series Tornadoes

Gustnadoes, Dust Devils, Fire whirls, Steam Devils, & Waterspouts

Most people are familiar with traditional tornadoes, the funnels spawned from supercell thunderstorms that pack the world’s highest wind speeds and can devastate homes or towns.

But one type of swirl wasn’t enough for a planet as magnificent and varied as Earth.

Vertical vortices come in myriad forms with fantastic names.

Beyond the traditional classification, the most commonly known is the waterspout.

Waterspouts

Also called fair weather waterspouts, these twisters are not simply tornadoes that form over bodies of water. Some scientists even call them non-tornadic waterspouts. Unlike traditional versions, a waterspout does not develop from a mesocyclone (spinning thunderstorm). Instead, they evolve on microscales thanks to wind shear near the water. Meteorologists believe they form from the bottom and eventually connect with a budding cloud. The spin and wind speeds associated with fair weather waterspouts are significantly tamer compared to those of traditional tornadoes. Waterspouts often display laminar walls, smooth funnels that can appear quite enchanting.

The same phenomenon can occur on land, in which case we call the twister a landspout. Forming from the ground to the cloud, these types of tornadoes are far less destructive than supercell tornadoes.

Traditional tornadoes can move over rivers, lakes, and oceans, or even begin their lives on those types of bodies. If the mesotornado happens over water, we sometimes refer to them as tornadic waterspouts, but they differ fundamentally from fair weather waterspouts.

Waterspouts most often originate in the tropics, specifically the Florida Keys, but can occur anywhere water exists. They’ve even happened at the Great Salt Lake!

Gustnadoes

Traditional twisters involve an interaction between an updraft into a mesocyclone and a downdraft from the associated supercell.

Sometimes, if no updraft is present but a thunderstorm’s downdraft is powerful enough, a pseudo-tornado might develop. We call these versions gust front tornadoes, or gustnadoes. If the downdraft hits a stationary pocket of warm, moist air, rolling effects can transpire, potentially crafting condensation clouds that might be mistaken for a tornado.

Their intensities and durations are usually far less severe than traditional tornadoes. Many meteorologists do not consider them to be true tornadoes, as they often do not connect from land to cloud.

Still, the powerful downbursts can often mimic small-scale tornadic damage.

Dust Devils

Also known as a dirt devil or whirlwind, a dust devil is a vortex that usually precipitates on sunny days without storms.

Whirlwinds can be thought of as the anti-gustnado, as they develop thanks to an updraft only. Sometimes, warm pockets of air near the ground suddenly rise and begin to twist. Dust devil formation occurs most often on flat, desert-like terrain, during clear skies, very little wind activity, and relatively cool atmospheric temperatures.

These rotational tubes can become quite long, though their durations are usually extremely short and their wind power relatively minor. Large dirt devils with strong winds (60 miles per hour+) can occur but are rare.

Like gustnadoes, because they do not connect the ground to a cloud, whirlwinds are not considered to be true tornadoes.

But, if you want to have the tornado experience with relative safety, a dust devil is the way to go!

Fire whirls

From possibly the least dangerous form of vertical rotation to the veritable inferno.

Fire whirls, also called fire devils, fire swirls, or fire tornadoes. combine a whirlwind and a conflagration.

And, yes, they are as terrifying and dangerous as they sound.

The updrafts in waterspouts, dust devils, and traditional tornadoes are all formed by warm or hot air. These movements typically occur because the air near the ground is warmer than the air above. In fire whirls, this gradient transpires because the ground is ablaze. The column of a fire devil can contain ash and suck a fire into the sky, causing a strikingly scary sight.

The largest fire swirls happen in wildfires. As if a towering, twisting inferno weren’t bad enough, the winds associated with this vortex can rip out trees, reaching speeds of 160 miles per hour or more.

As you might guess, where dust devils leave nearly no destruction or loss of life, fire whirls have annihilated large swaths of land and taken many lives. In 1923, Japan’s Great Kanto earthquake spun up a fire whirl that killed 38,000 people in 15 minutes! Fire bombings and nuclear blasts during World War II produced numerous fire devils. More recently, wildfires have created some monstrous fire whirls. In 2003, an example in Australia flash-burned 300 acres in 0.04 seconds, reaching the wind speeds of an EF3 tornado. In 2015, in Canada, a fire whirl caused an aircraft fighting wildfires to crash. In 2017, a New Zealand wildfire spawned a whirl more than 330 feet high.

Needless to say, though these vortices would likely be a once-in-a-lifetime sight, you don’t want to be anywhere near them.

Steam devils

Perhaps the most intriguing form of vertical vortex belongs to the steam devil.

Like waterspouts, this phenomenon occurs over water, but the formation mechanism is markedly different.

Steam devils might be described as fog whirlwinds. If the temperature of a body of water is markedly different from the air above it and a wind blows, an updraft that morphs into a vortex can transpire. If “fog steamers” – non-rotating columns of fog – are present they can become sucked into the vortex and become visible as a steam devil.

When viewed on a horizontal plane, steam fog assembles hexagonal cells, forming a honeycomb pattern. In this setup, three tiles meet at a point, a juncture at which the steam devil forms.

Steam devils happen most frequently in the Great Lakes or off the American Atlantic coast, as cold air meets the Gulf Stream. Intriguingly, another hotspot for steam devil activity is Yellowstone. The warmth of the geysers can collide with cold northern air, producing steam devils!

Like the dust devil, this vortex version is nearly harmless.