Tornadoes hit Australia, with more on the way this spring/summer
You may be surprised to learn that Australia annually experiences tornadoes powerful enough to lift cars and cattle into the air -here’s what you need to know about these towering twisters
READING LEVEL: GREEN
Tornadoes ripping across the landscape – some of them strong enough to lift cows and cars in the air – are not unique to America. In fact, they happen in Australia more often than you might think.
A dramatic video captured by a member of the NSW Rural Fire Service over the weekend shows a powerful tornado forming north of Gunning, about an hour north of the ACT border, before sweeping across the NSW tablelands. Saturday’s twister left some damage along the way, with RFS photos showing fallen trees scattered across roads. The striking weather event* impacted communities in Goulburn, Sutton and Yass.
The Bureau of Meteorology* predicted more tornadoes would hit NSW and Queensland over the coming week. But what exactly are tornadoes, how do they form, and how can they cause such widespread destruction in regional areas?
WHAT IS A TORNADO?
A tornado is a weather event where a column of air comes down from a cloud and touches the ground while violently rotating, according to the Bureau’s knowledge centre.
To be classified as a tornado by the Bureau, the column of air must be connected to both the ground and a cloud simultaneously*. Otherwise, it is a “gustnado” or dust devil, which can form on clear days.
Tornadoes connect to tall, puffy clouds or thunderstorm clouds, and they are often tens of metres wide, Bureau of Meteorology senior meteorologist* Dean Narramore said.
“Maybe as wide as a house, or a bit bigger, up to the size of a football field or larger, up to a kilometre or two wide,” Mr Narramore said.
They generally last for a few minutes at a time and cause extensive* damage. What makes them one of the most destructive weather events is the speed of winds inside the cloud cone, which can go beyond 300 km/hr.
This wind speed can do a lot of damage to homes and other structures* in the affected areas, sometimes picking up cars and even farm animals into the air.
“That is true … the winds in these tornadoes can be very strong,” Mr Narramore said.
“Once you get winds up to that speed, 150, 200, 250 km/h, that is normally strong enough to blow over or pick up cars, trucks and boats.”
HOW DOES IT FORM?
When warm, moist air at the surface combines with the cold air and strong winds in the upper levels of the atmosphere, it makes the perfect conditions for a tornado to form.
These conditions produce what meteorologists call “supercell thunderstorms”*, which are very organised, rotating thunderstorms.
The spinning area hangs below the main storm, creating a wall cloud, where a violently rotating column of air starts to form and head downwards, eventually touching the ground.
Once it hits the ground, it pulls in the wind around it, acting like a vacuum, pulling in air, dust, dirt and debris.
Mr Narramore said tornadoes “generally, only last for minutes at a time, and of course can cause quite a lot of damage.”
WHAT COLOUR IS A TORNADO?
If the column of air is not moving through dirt and mud, it is generally grey and classified as a cloud called a “condensation* funnel”.
“It’s just the air that has become saturated, and turned into a condensed funnel,” Mr Narramore said.
“But once it starts getting deeper and stronger, it starts picking up all that dirt and mud, which is making it brown, or debris, which shows you that it’s obviously there,” he said.
“Eventually sometimes it can condense, which means the air’s saturating* to 100 per cent humidity*, which is the same process a cloud goes under, which then gets that grey condensation funnel that we sometimes see with tornadoes.”
Sometimes tornadoes can be invisible if they have not condensed or have not yet picked up enough debris. Otherwise, a tornado takes on the colour of whatever debris or mud it picks up or destroys, Mr Narramore said.
In one extremely rare case, Americans were treated to a pink tornado, after it destroyed a flower farm and picked up all the red and pink roses.
FREQUENCY IN AUSTRALIA
About 1200 tornadoes rip through the United States every year. By comparison, Australia’s average of 40 to 60 tornadoes is very small – and most of them happen in the outback.
“It’s a much smaller number than America,” Mr Narramore said. “But a number of them occur in places where no one lives. So we might only see about 10 or 20 tornadoes a year, on video and footage, if someone’s out and about on their farm or property when it occurs.”
Historical data from the Bureau suggests between 30 to 80 tornadoes form in Australia each year, with a Bureau estimate of around 50 tornadoes travelling through the country every year. However, the actual figure is not known due to under-reported weather events in remote regions.
While it is rare for multiple tornadoes to strike a single Australian region at the same time, it is still possible and has been recorded in the past.
Seven tornadoes ripped through South Australia a decade ago, on September 28, 2016, leading to a statewide power outage.
HOW TO SPOT ONE A TORNADO
While meteorologists can predict the right conditions to produce a tornado, they can’t predict exactly which thunderstorms will produce one, until just before it happens.
The Bureau uses radars to look at storms vertically to see if they are spinning, and to observe wind conditions on the surface.
If meteorologists do see any signs of supercell thunderstorms and wind on the surface, they issue tornado warnings.
If you live in the regions, you can spot a potential tornado when you see a very dark sky with heavy thunder and lightning, and you see a wall cloud hanging beneath the storm.
If you see the wall cloud spinning, that means the tornado is about to form and move very quickly. That’s when it’s time to move swiftly indoors to a safe place.
POTENTIAL TORNADOES THIS WEEK
Mr Narramore said Tuesday was “looking like a pretty big day for some severe thunderstorms in Queensland and NSW.”
“Some of them might have a tornado,” he said.
Prime tornado season is across spring and early summer. Starting from October, the season carries into November and December.
WATCH THE VIDEO OF TORNADO HITTING NSW
POLL
GLOSSARY
- weather event: occurrence of a specific weather phenomenon or extreme weather condition
- meteorology: the science and study of the processes that cause weather events/conditions
- simultaneously: happening at the same time
- meteorologist: someone who studies meteorology,
- extensive: covering or affecting a large area, scale, or scope
- structures: buildings or other sites built or constructed from several parts such as bridges
- supercell thunderstorm: a severe thunderstorm that rotates and spins
- condensation: the process of water vapour turning into liquid water
- saturating: soaking thoroughly or filling something to its maximum capacity
- humidity: the amount of water vapour present in the air
EXTRA READING
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Why landslides lead to flashfloods?
QUICK QUIZ
- How many tornadoes hit Australia each year?
- What is a wall cloud?
- Can tornadoes pick up cars and cattle?
- Which state was affected by a tornado last week?
- How can you spot a tornado?
LISTEN TO THIS STORY
CLASSROOM ACTIVITIES
1. Labelled Diagram of a Tornado
Create a labelled diagram showing how a tornado forms including the terms warm air, cold air, a thunderstorm, rotating air and the tornado funnel.
Time: allow 15 minutes to complete this activity
Curriculum links: English, Science, Personal and Social, Critical and Creative Thinking.
2,Extension
Why do tornadoes occur in some parts of the world more frequently than others? Give the scientific explanation.
Time: allow 10 minutes to complete this activity
Curriculum links: English, Science, Personal and Social, Critical and Creative Thinking.
VCOP ACTIVITY
Read with Kung Fu punctuation
Pair up with the article between you and stand up to make it easy to demonstrate your Kung Fu punctuation.
Practice reading one sentence at a time. Now read it again, while acting out the punctuation as you read.
Read and act three sentences before swapping with your partner.
Take two turns each.
Now ask your partner to read a sentence out loud while you try and act out the punctuation. Can you keep up? Swap over?
Try acting out two sentences – are you laughing yet?