Hurricanes and cyclones 101: Know the difference
Tropical storms have also made appearances in South Africa, here is what you need to know if the next one strikes.
Cyclone Dineo recently caused destruction in its wake when it crossed South African borders.
Many are confused by the difference between hurricanes and cyclones.
• Read: Heavy rain and flooding may follow Dineo: tips for staying safe
This is the second of six weather articles related to natural disasters.
• Also read: Earthquakes 101: What you need to know
Here is a rundown to give you the necessary facts to be able to call a spade a spade.
What is it?
A hurricane and a cyclone are the exact same weather phenomenon, a big storm moving in a circular pattern with exceptionally strong wind, usually accompanied by rain or hail.
What many people may not know is that the reason for the confusion, all lies with location.
Yes, depending on your geographical location on earth, the storm would have a different name.
According to the National Oceanic and Atmospheric Administration (NOAA) of the US Department of Commerce, different names are used in different places.
“In the Atlantic and Northeast Pacific, the term ‘hurricane’ is used. The same type of disturbance in the Northwest Pacific is called a ‘typhoon’ and ‘cyclones’ occur in the South Pacific and Indian Ocean.”
The Atlantic and Indian oceans meet at Cape Agulhas in the Western Cape, meaning that in about a quarter of South Africa, such a storm would be known as a hurricane and the rest of South Africans would call it a cyclone.
Seeing as Gauteng is on the Indian Ocean side of the country, we’d be the ‘cyclone group’.
How does it manifest?
According to Nasa’s Space Place a cyclone is only formed over warm ocean waters near the equator.
The warm, moist air over the ocean rises upward from near the surface.
As the warm air continues to rise, the surrounding air swirls in to take its place and when the warm air cools off, the water in the air forms clouds.
The clouds and wind spins and grows, fed by the ocean’s heat and water evaporating from the surface.
Storms that form north of the equator (northern hemisphere), spin counterclockwise whereas storms that form in the southern hemisphere rotate clockwise.
This difference is due to the earth’s rotation on its axis.
When the winds in the rotating storm reach 63km/h, it is called a tropical storm, when the speeds reach 119km/h, it is officially a tropical cyclone.
What are the dangers?
Cyclones usually weaken when they hit land, however, they can often move far inland and cause a lot of wind damage.
The tropical cyclone categories are:
1. From 119km/h to 153km/h, the damage at landfall is minimal.
2. From 154km/h to 177km/h, the damage at landfall is moderate.
3. From 178km/h to 208km/h, the damage at landfall is extensive.
4. From 209km/h to 251km/h, the damage at landfall is extreme.
5. From 252km/h or higher, the damage at landfall is catastrophic.
Cyclones cause storm surges, heavy rainfall, inland flooding, high winds and rip currents.
What to do during a cyclone?
According to the Australian Government’s Bureau of Meteorology, the following applies when a cyclone strikes
• Disconnect all electrical appliances.
• Stay inside, clear of windows, in the strongest part of the building such as the cellar, hallway or bathroom.
• If the building starts to break up, protect yourself with mattresses, rugs or blankets under a strong table or hold onto a solid fixture.
• If driving, stop the vehicle with the handbrake on and in gear, keep clear of trees and power lines. Stay in the vehicle.
Look out for the third article on natural disasters – Tornadoes 101: When the unexpected happens.
