Cyclone Yasi

By Bella

What causes tropical cyclones to form and what characteristics of them do we need to be concerned by?

A cyclone is formed over tropical seas. Winds from opposite directions meet. This air is heated by the warm seas and so evaporates moisture from the ocean. This warm air rises up rapidly, cools and condenses to form clouds and produces an area of very low pressure. When moisture and air mix, it makes a collection of thunderstorms from which a cyclone can develop. Water needs to be at least 26 degrees warm so a tropical cyclone can develop.

More air is sucked in to take its place, and it too is heated and rises rapidly. This sucking in and rising movement of the air produces spiraling clouds. Eventually, an enormous storm system is built up, which can spread over two hundred kilometers. Heavy rain falls from the clouds. There is much thunder and lightning and the fast winds whip up the waves of the ocean.

In the middle of this system, air moves down. This produces a patch of drier, calm weather with few clouds. It is called the 'eye' of the storm and can last for an hour before the fierce winds and torrential rainstorms sweep in again. When the cyclone hits land, it soon weakens, as there is no warm, moist air to 'feed' the storm.

›There are various trigger mechanisms required to transform these cloud clusters into a tropical cyclone. These trigger mechanisms depend on several conditions being 'right' at the same time. The most influential factors are:

›a source of warm, moist air derived from tropical oceans with sea surface temperatures normally in the region of, or in excess, of 27 °C;

›winds near the ocean surface blowing from different directions converging and causing air to rise and storm clouds to form;

›winds which do not vary greatly with height - known as low wind shear. This allows the storm clouds to rise vertically to high levels;

›sufficient distance from the equator to provide spin or twist.

KGI'S MOVEMENT - movement of the wind LOCATION- have to be near the sea REGIAN - in the tropics



What was the pathway of Yasi and how did this affect the cyclone?

It spent a long time over the sea, gaining intensity which meant that it could, ‘and did’, keep it’s strength for a much longer time once it crossed land. Most cyclones tend to lose intensity quickly once they hit land. It was one of the largest and most intense cyclones to ever hit Queensland.

KGI: Location, Movement, Scale, Spatial change over time

How were the natural and cultural landscapes affected by Yasi?

Natural and cultural landscapes were affected by cyclone Yasi. Parks were destroyed leaving a bug mess to clean up after the tragic disaster. Many forests and National parks had fallen and tress lost their branches, leaves and canopies ripped from the trees. Rangers very quickly got to work on reopening the parks. An instant worry that came with the destroyed national parks was the animals. Both the endangered southern cassowary and the endangered mahogany glider were major concerns for rangers. The endangered southern cassowary lives off of canopy fruit and as the canopies were all sadly ruined in the cyclone, there was a major worry that they would have trouble in these awful conditions. It would be months before the source would go back to normal and the cassowary population would be good. The endangered mahogany glider lives in lowland sclerophyll forest between Townsville and Tully. This area was severally damaged during cyclone Yasi. Tropical rainforests in northern Queensland were also destroyed, nevertheless they recovered by themselves from the cyclone. Some of the species of plants in the forests were already ready to spring into flower just after the cyclone and started to fill the gaps that had become present in the canopies. The recovery could be seen improving day-by-day very easily.

KGI: Location, Distance

What were the characteristics of Yasi?

A cyclone is formed over tropical seas. Winds from opposite directions meet. This air is heated by the warm seas and so evaporates moisture from the ocean. This warm air rises up rapidly, cools and condenses to form clouds and produces an area of very low pressure. When moisture and air mix, it makes a collection of thunderstorms from which a cyclone can develop. Water needs to be at least 26 degrees warm so a tropical cyclone can develop.

More air is sucked in to take its place, and it too is heated and rises rapidly. This sucking in and rising movement of the air produces spiraling clouds. Eventually, an enormous storm system is built up, which can spread over two hundred kilometers. Heavy rain falls from the clouds. There is much thunder and lightning and the fast winds whip up the waves of the ocean.

In the middle of this system, air moves down. This produces a patch of drier, calm weather with few clouds. It is called the 'eye' of the storm and can last for an hour before the fierce winds and torrential rainstorms sweep in again. When the cyclone hits land, it soon weakens, as there is no warm, moist air to 'feed' the storm.

Cyclone Yasi formed 330 km off the northwest coast of Fiji. It was first classified as a tropical disturbance on 26th January 2011. By the time it was classified as a tropical cyclone, it was located approximately 370 km northeast of Vanuatu. Yasi then travelled across the Coral Sea and hit mainland Australia near Mission Beach at midnight on the 3rd February, 2011.

Between Vanuatu and Australia, the only land mass is New Caledonia. This means that Cyclone Yasi travelled approximately 2396 km over warm water, all the time building in energy and mass. At time of landfall, it was a massive wall of wind, supercharged from its prolonged journey over warm water.

Cyclone Yasi was one of the most damaging cyclones to have ever struck Queensland. This cyclone brought treacherous winds; heavy rains that caused a widespread floods and enormous destruction. It was recorded that at South Mission Beach, 143km south of Cairns, 470 mL of rainfall occurred within 24 hours. Buildings and homes were flooded throughout this region as the local residents reported that their houses were at least 1 meter underwater.

The highest wind speed recorded during Cyclone Yasi’s path was at midnight near Lucinda Point at 185km/h. The strong winds were not the only threat, as tropical cyclones are known to cause storm surges. Tidal waves of about 5 meters high were recorded, these were the largest waves recorded for Cyclone Yasi. Boats at the marina were washed up onto the shore and piled on top of one another. The storm surges travelled 300 meters inland from Cardwell hitting Cairns and Townsville, flooding the grounds with murky brown water.

KGI: Location, Movement

Aerial footage of Cyclone Yasi devastation

Focus on two effects of Yasi for example: economic impact upon banana plantations. Describe the effect on these aspects and describe the distribution of this impact. For example: the location of banana plantations affected.

Banana and sugarcane plantation

Banana crops were destroyed. When cyclone Yasi hit banana prices shot up, from $1-2 per kilogram to $15 per kilogram. Prices have never been that high even since cyclone Larry.

Not only Banana crops were destroyed so were sugarcane plantations. Sugarcane growers expected more the $500 million to be wiped off their $2.5 billion industry. More than 75% of Australia’s banana and sugarcane crops were demolished because of cyclone Yasi.


What changes for the region and for wider Australia have occurred due to Cyclone?

The changes cyclone Yasi caused were, a hand full of things like just the immense devastation of the cyclone hitting, people loosing their homes, business, foods/crops, and just everything they love and own. By cyclone Yasi hitting farmers lost a lot of their crops and they machinery which ment cyclone Yasi really destroyed they way of living not being able to earn an income. it also caused unemployment by not needing many farmers from like lack of banana's. By the farmers loosing their crops and machinery also effected all of Australia by the rising price of banana’s. People all over Australia still bought these highly priced banana's because they wanted to support the farmers who had lost everything.
KGI: Location, Spatial change over time, Region


Banana crop devastated by Yasi