Understanding Tino
IF you are in your 40s like me, chances are you’ve been through at least a dozen cyclones in your lifetime. So I would be correct if I said you have heard of names such as Kina, Oscar, Raja, Eric, Nigel, Sarai, Winston and Ofa, Gavin and Ami. Some of the names will ring a bell.
One challenge I often face when listening to the language used in weather bulletins, is trying to comprehend what certain words mean and what a cyclone is.
This week, as we keep a track on cyclone Tino’s development and path, I think it would be sensible to discuss about cyclones.
To subdue an enemy it is important to know the enemy, military strategists will tell you. Likewise, to deal with cyclones it is useful to first understand what they are all about.
According to literature on weather, a storm is any atmospheric disturbance and it can be a thunderstorm, tornado or a cyclone. All three are examples of storms.
Some storms are weak, some are strong and some may be extremely powerful. They occur naturally on earth and all the time.
Experts say, on average there are 16 million storms worldwide annually and as you read this article, 2000 storms are taking place in various parts of the world.
Storms occur around the equator. Why? Because it is hot. They are called different names, depending on location.
The scientific term used to describe all storms is tropical cyclone because they form over the tropical ocean regions.
Tropical cyclones that form over the Atlantic Ocean or eastern Pacific Ocean (the Americas) are called hurricanes.
Those that form in the eastern hemisphere (Asia) over the north western Pacific Ocean are called typhoons. Storms that form specifically over the Indian Ocean are called monsoons while the violent storms that we often face in the Pacific or south of the equator are called cyclones.
Regardless, of what storms are called in different parts of the world, they are formed in the same way. To form they all need the same fuel – warm and moist air.
When air over the warm oceans near the equator get heated up, it rises and when it rises high up in the atmosphere it cools down and condenses to form clouds.
Cumulus clouds are associated with good weather and clear blue skies. At this time, you’d probably want to sun out your beddings and clean up around the house.
But as more vapour rises into the atmosphere and condenses to form more clouds, the cumulus clouds become cumulonimbus clouds which can cause a storm. A thunderstorm brings rain, thunder and lightning.
Once a group of thunderstorms join together under the right atmospheric conditions for an extended period of time, they can organise into what is known as a tropical depression.
Winds at the centre of the system during a depression are between 20 to 34 knots.
Thirty four knots may sound negligible. However, remember that it can take a few hours to two days for a system to develop from a tropical depression stage to a tropical cyclone.
During this period of intensification it picks up wind speed and strength, and the more fuel it gets the stronger it becomes.
Tropical cyclone develops when highly turbulent cumulonimbus clouds gather momentum and form a spiral pattern, where a dense central cloud band wraps around a calm, cloud-free “eye”.
The eye can have a diameter of up to 60 km. If that is the eye then you can imagine the widespread damage a cyclone can cause when it moves along its track.
A tropical cyclone can have wind speeds of more than 64 knots.
In a Category One cyclone, the strongest winds are gales with gusts of 90-125km per hr which can cause negligible damages to houses, crops and trees.
Category Two — there can be significant damage to signs and tree, heavy damage to some crops, risks of power failure and small boats may break from their moorings.
A C2 cyclone’s strongest winds are destructive winds with momentary gusts of up to 125164km/hr.
Category 3 — can cause some roof and structural damage, and power failures are likely. A C3 cyclone’s strongest winds are very destructive winds with momentary gusts of up to 165-224km/hr.
Category 4 — can cause significant loss and structural damage, widespread power failure and dangerous airborne debris. A C4 cyclone’s strongest winds are very destructive with momentary gusts of up to 225-279km/hr.
Category 5 — is extremely dangerous with widespread destruction. Its strongest winds are very destructive winds with momentary gusts of more than 280km/hr.
STC Winston was the strongest tropical cyclone to make landfall in Fiji and the South Pacific Ocean basin in recorded history. STC Winston rapidly intensified, reaching Category 5 and caused extensive damage on many islands and killed 44 people.
A total of 40,000 homes were damaged or destroyed and approximately 350,000 people — about 40 per cent of Fiji’s population— were significantly impacted by the storm. Total damage from STC Winston amounted to $F2.98 billion ($US1.4 billion).
Tropical cyclones usually weaken when they hit land, because they are no longer being “fed” by the energy from the warm ocean waters.
However, when they move inland, they dump many inches of rain and cause lots of wind damage before they die out completely.
You are probably wondering who and how are cyclones named. In the South Pacific Ocean, naming is done by the Fiji Meteorological Service and the New Zealand MetService, depending on where the system is located.
Names follow an alphabetical order (hence Sarai and Tino, so the next could start with U). Names are pre-chosen and can be recycled.
Cyclone names that cause significant damage are retired and never used again. The retired names of cyclones since Winston in 2016 are Cook, Donna, Gita, Josie and Keni.
Cyclones are unpredictable by their very nature, so it pays to be prepared at all times.
Our cyclone season is from November to April.
One of the best ways to be prepared is to keep an eye and ear on local weather bulletins issued by the FMS through the country’s various media outlets.
Until next week, have a safe and productive week!