Tornadoes can be terrifying — whether you experience them or only see images of the aftermath.
Most tornadoes are short-lived and harmless. A tornado that is not normal and strikes humans can cause severe damage, even death.
This was what happened in the United States when a series tornadoes struck in early December. It left a trail of destruction that ran from Arkansas to Kentucky. Dozens of people were killed and many are still missing.
The US National Weather Service described one of the tornadoes as “potentially historic” — due to it possibly being on the ground for the longest distance on record.
How does a tornado form?
Scientists are aware of the basic ingredients that cause tornadoes but are still trying to figure out what causes them.
Walker Ashley, an atmospheric scientist from Northern Illinois University, said that “the truthful answers are we don’t know”.
Ashley is — what you might call — a storm chaser.
“I spend about a month out of the year chasing these weather phenomena, and they never want me to.” [turn into a tornado]Ashley said to DW that she is sitting down when Ashley is speaking.
Certain weather conditions
Tornadoes are formed in very specific weather conditions. A supercell is a rotating thunderstorm that causes tornadoes. A supercell can bring lightning and strong winds, hail and flash flooding.
If the wind speed or direction is different at different altitudes, then you can get a “wind shear.”
Although wind shears are usually harmless, they can cause air currents spin and create a horizontal tube out of air. This is a common phenomenon in supercell thunderstorms but it’s not yet a tornado.
Sometimes, a storm can suck up the tube of air until it becomes horizontal. It’s known as a mesocyclone when it happens.
This is still not a tornado. To form a tornado, there must be spinning air near to the ground.
The stronger the air tube rotates, the closer it can touch the ground. It is more likely to turn into a tornado. Ashley says: Think about it as a figure skater.
“When a figure skater extends their arms, they slow down.” Ashley says that figure skaters who bring their arms in accelerate. “And what a storm is does is it takes that same rotation, tilts the vertically and stretches them. It increases the rotation when it stretches it.
This causes warm air to rise and cool air to sink, blowing across land. The air near ground spins if there are enough sinking and rising gusts.
The tornado turns darker once it is vertical. It picks up any dust, debris, or other obstructions that get in its path. A strong tornado can even pick up houses, animals, and cars.
Why is it so difficult to predict tornadoes?
The US considers spring tornado season, but it can strike at anytime, as in the December 2021.
They are also difficult to predict, as they are smaller than other extreme weather events. They are therefore difficult to observe.
“If we think about all the different hazards we have like hurricanes, droughts, floods, tornadoes might be one of the smallest,” says Ashley, “even the most violent tornadoes are, at most, a half-mile (800 meters) wide — they occur typically in the order of seconds to minutes.”
Therefore, tornadoes are often found below certain levels that meteorologists use for modeling, observing and predicting weather events. Ashley states that scientists can simulate tornadoes using computers but that it requires a tremendous amount of computing power.
It is important to be able predict extreme weather events so authorities can issue warnings and give people the chance to escape to safety. What can they do to prepare?
Scientists monitor supercell thunderstorms for warnings and use radar technology, which measures the speed at which the mesocyclone rotates, to issue them. It is more likely to become a tornado if it rotates faster and is closer to the ground.
“The majority of the tornadoes and storms are not severe.” [we observe]”We are on the cusp. It’s almost like a storm is moving like crazy in the midlevels. But, just because it’s rotating high doesn’t necessarily indicate it’s going towards the ground,” Ashley states.
Ashley states that researchers “don’t have very accurate observations at the lowest levels of atmosphere,” and that is a crucial piece of the puzzle.
What does climate change mean for tornadoes?
The role of climate in tornadoes is complicated. Ashley insists that it is not a matter of whether climate change causes tornadoes. The question is whether or not climate change has contributed to the exact “ingredients”, which are necessary for tornadoes form.
“As it pertains to climate change, some of the essential ingredients that make up the process are known. [contribute to]Ashley says severe thunderstorms can also produce hail and tornadoes, which is increasing.”
This is evident from modeling, which shows that it is true in the United States. However, it may also be true in Europe and the UK.
Edited By: Zulfikar Abany