A twisting column of fire known as a “fire devil” leapt out of a wildfire in Portugal, making an already scary-looking blaze appear even more dangerous.

Just as California has been battling wildfires in recent days, these forest blazes have cropped up in Portugal too. On Sunday in Portugal, the high winds swept up some of the flames into a swirling vortex called a fire devil, but also known as a fire whirl or a fire tornado.

The latter name, while it may seem visually proper, is not entirely accurate — the phenomenon is closer to a fiery version of a dust devil than a tornado. Dust devils are thin spirals of air that form in hot and windy conditions — when a certain spot on the ground is hotter than those around it, it heats up adjacent air that then rises upward and can be thrown into a sideways rotation if a blast of air hits it from the right angle. The spiral picks up small material like dust as it twists up.

With a fire devil, there is a similar underlying process: A particularly hot area on the ground makes heated air rise and, with a blast of wind, creates a swirling column of air that carries things upward from the ground — in this case, fire and ash.

“I would just call them fire vortices but that doesn’t sound so sexy to the public, so I would call them fire devils,” climatologist Mark Wysocki said, according to Live Science. “These plumes form in a very small region over the land. … They start to rise very rapidly, and as things start to rise, they suck the surrounding air in like a vacuum. Then you get this twisting that begins to resemble a vortex.”

The higher it goes, the thinner and faster it gets.

Tornadoes, on the other hand, are much larger and form during thunderstorms. While scientists don’t completely understand the processes behind the funnel’s formation, it could be related to sections of atmosphere with different conditions meeting one another, like different wind speeds, moisture levels and temperatures.

Fire devils are not common occurrences but can whirl up during a wildfire because of the heat and wind conditions during those events. They occur in dry areas, such as when a place gets little rainfall. When the vegetation is dried out enough, a spark from a strike of lightning, a poorly controlled campfire or a smoldering cigarette butt can set plants ablaze, with high winds helping to spread the flames.

Wildfires can create walls of flame that reach dozens of feet into the air. The heat from the fire is intense, one of the many hazards to human life and anything else in its path.

The Express reported that Portugal has seen numerous wildfires this year, due to a dry and hot summer. That includes five large fires around the nation this weekend, which about 1,000 firefighters were trying to control. One blaze in June killed 64 people, some of them on a bridge that caught fire.