Cyclones are some of the most powerful and destructive weather events on the planet. But how do they form? What makes one more dangerous than another? And who gets to decide what they’re called? Let’s break it all down in simple terms.
How Do Cyclones Form?
Cyclones don’t just appear out of nowhere—they need the right ingredients to form. The key factor? Warm ocean water. The sea surface temperature must be at least 26.5°C for a cyclone to develop.
Here’s what happens next:
- A cluster of thunderstorms gathers over the ocean.
- These storms suck up warm, moist air, which then rises into the atmosphere.
- As the warm air rises, the pressure beneath it drops. This creates a low-pressure system.
- Surrounding air rushes in to fill the gap, which causes the system to intensify.
- When wind speeds hit 63 km/h, it is officially classified as a tropical cyclone.
Cyclones always form over the ocean, not land, because they rely on warm water as their energy source. Once they move over land, they start to weaken because they lose their fuel.
Why Do Cyclones Spin?
Ever noticed that cyclones spin in different directions depending on where they are? That’s thanks to the Coriolis effect, caused by Earth’s rotation.
- In the Southern Hemisphere, cyclones spin clockwise.
- In the Northern Hemisphere, they spin anti-clockwise (where they’re called hurricanes or typhoons).
Even though they have different names in different regions, hurricanes, typhoons, and cyclones are actually the same phenomenon—just with regional differences in naming.
The Structure of a Cyclone
A cyclone isn’t just a chaotic storm; it has a distinct structure.
- The Eye: The calm centre of the storm, typically around 40 km wide. The air here is sinking, which is why it’s relatively peaceful.
- The Eye Wall: This is the most dangerous part of a cyclone. Towering clouds and fierce winds surround the eye, causing the worst damage.
- Rain Bands: These are the long, spiralling bands of clouds and rain that stretch out for kilometres, bringing heavy rainfall and flooding.
Sometimes, people mistakenly believe a cyclone has passed when the eye moves over them, only to be caught off guard when the second half of the storm arrives.
Cyclone Categories: How Are They Rated?
Not all cyclones are created equal. Some bring mild wind and rain, while others leave a trail of destruction. The severity of a cyclone is measured using wind speed, classified into five categories:
1️⃣ Category 1 (Up to 125 km/h)
- Minor damage, but can blow over small objects and damage crops.
- Boats may be dragged from their moorings.
2️⃣ Category 2 (125–164 km/h)
- Can damage homes, break windows, and uproot trees.
- Power lines may be brought down.
3️⃣ Category 3 (165–224 km/h)
- Now classified as a severe cyclone.
- Powerful enough to rip roofs off buildings and turn debris into dangerous missiles.
4️⃣ Category 4 (225–279 km/h)
- Widespread destruction.
- Buildings suffer major structural damage, and power poles are likely to be torn down.
5️⃣ Category 5 (280+ km/h)
- Total devastation. Houses flattened, infrastructure destroyed, and massive storm surges.
Cyclones can intensify very quickly. For example, Cyclone Marcus went from a Category 1 to a Category 4 in less than 24 hours. That’s why constant monitoring and early warnings are crucial.
The Hidden Danger: Storm Surges & Flooding
While strong winds make headlines, the biggest killer in a cyclone is often the storm surge. This happens when strong winds push seawater inland, causing flooding along the coast.
If a cyclone makes landfall during a high tide, the impact is even worse. A tragic example was Hurricane Katrina in 2005, where storm surges devastated New Orleans.
Apart from storm surges, flash flooding is another major risk. Heavy rain can wash away roads, cars, and even people.
Cyclones in Australian History
If you live on the Queensland coast, chances are you’ve experienced a cyclone or two. Some of the most devastating cyclones in Australian history include:
🌀 1954 Gold Coast Cyclone
- Estimated 26 to 30 deaths.
- A staggering 900mm of rain fell in one day at Springbrook.
🌀 Cyclone Yasi (2011)
- Category 5, 285 km/h winds.
- Cardwell was hit by a 5-metre tidal surge.
- Dunk Island was completely destroyed.
🌀 Cyclone Larry (2006)
- Category 5.
- 10,000 homes damaged near Innisfail.
- Total damages exceeded $1.5 billion.
These storms serve as a reminder of just how unpredictable and destructive cyclones can be.
Who Decides the Names of Cyclones?
Ever wondered how cyclones get their names? It’s not random!
In Australia, the Bureau of Meteorology (BoM) is responsible for naming cyclones. Each season, they have a pre-approved list of names, alternating between male and female names.
Fun Facts About Cyclone Names:
✔ If a name is linked to a famous person, they skip it (imagine “Cyclone Beyoncé”!).
✔ If a cyclone causes massive destruction, its name is retired forever.
✔ That’s why we’ll never see another Cyclone Tracy or Cyclone Larry.
Be Prepared, Stay Safe
Cyclones are a force of nature that can’t be stopped, but with modern technology, we can predict them, track them, and prepare for them.
If you live in a cyclone-prone area, always stay updated with the Bureau of Meteorology’s alerts and have an emergency plan ready. It only takes one storm to change everything.
Stay safe, stay informed, and never underestimate the power of Mother Nature.
Source: ABC News Australia
