Building Construction, Renovation, Maintenance & Advice

All about Cyclones Hurricanes and Typhoons

"How to take the skin off a rice pudding"

Been a bit of flatulence around recently. I was woken up the other night by the rude sound of passing wind, I turned over but it made no difference. I think it must have been the sound of someone’s roof leaping from one house to another that caused a minor disturbance to my peace of my mind so eventually I got up and looked out of the window. What a sight, banana trees were shredding and palm trees bending over at 45 degree angles. There was more wind than Silvio Berlusconi in a Eurozone meeting and I could have sworn I saw a goldfish or two.

It was reminiscent of a mini cyclone I once got caught in many years ago in Brisbane. Brisbane doesn’t usually get cyclones but this was a freak of nature that caused a lot of damage and made a lot of people wish they had worn their brown trousers that day.

I was caught in my car. I saw it coming up a side street, a solid wall of white spray. I drove to get away but it was clear that I wasn’t going to make it so I found a place I thought would be a safe area away from trees and sat it out. There comes a point doesn’t there when the exhilaration at the shear power of nature starts to turn into a nagging doubt, the start of a slippery slope to mild consternation and even a slight softening of the stiffness of the upper lip.

I was right in the path of the storm and got the double whammy, incredibly strong winds blew in one direction taking branches off trees and making wheelie bins airborne. I watched transfixed as all manner of things blew past, cane chairs, pieces of plastic, the odd granny or two. Then, suddenly, it stopped. There was a dead calm and I could see blue sky above but then, just as suddenly as it had stopped, strong winds struck again this time blowing in completely the opposite direction. The meteorological trauma moved off towards the centre of the city leaving devastation in its wake.

The wind that hit my house the other night was getting on for a similar strength, it is very unusual to get winds that strong in Bali but we should remember that we are, in fact, in a cyclone area. There are seven recognised worldwide tropical storm “basins” where storms occur on a regular basis, Bali is in the Southeast Indian/Australian basin.

Our recent wind was caused by cyclone Iggy (who on earth dreamt up that name?), a category 1 tropical cyclone with winds up to 60 kilometres an hour which moved across the Indian Ocean between Indonesia and Australia and killed 7 people mostly from falling trees

What are Cyclones, Hurricanes and Typhoons?

Cyclones, Typhoons and Hurricanes are effectively the same thing. They are, like political parties, formed by hot air. They develop when sea water temperatures rise (usually in spring and summer) to above 26.5 Degrees celsius. Hot air rises taking evaporated sea water with it and as it rises higher in the atmosphere it cools, the water condenses out forming rain and the action of condensation releases heat which further fuels the cyclone. The rising column of air causes a reduction in air pressure in the centre which draws air into the bottom of the cyclone further increasing the rate of evaporation of the sea water, the storm progressively increases in intensity.

The Coriolis effect, tropical storms and water down the plug hole

The turning of the earth starts the rising air rotating, in the northern hemisphere tropical storms are called Typhoons or Hurricanes and turn in an anticlockwise direction while in the southern hemisphere they are called Cyclones and turn clockwise. This turning motion (just like your bathwater going down the plughole) is known as the Coriolis effect after a man called Eric Frottington (no just kidding, he was really a Frenchman called Gaspard Gustave Coriolis) who was a very clean but rather wrinkled man and wrote a mathematical paper in 1835 which made him very happy and a bit famous.

“You’re breakfast’s ready.”
“Sorry dear just having another bath.”
“What another one? That makes 16 this morning. You're going all wrinkly”

Where do Tropical storms form?

Tropical storms need to form more than 5 degrees of latitude away from the equator (Bali is 8 degrees south) for the Coriolis effect to start the winds circulating. Most tropical storms form between 10 and 30 degrees away from the equator with 87% forming no more than 20 degrees away from the equator.

Tropical storms move in a westerly direction and, in the absence of strong winds, tend to move towards the poles (South in the southern hemisphere). They drift around for a while (up to 30 days) until they hit land and then the absence of warm sea water makes them collapse.

How large can they get?

They can get quite big (even larger than a Jakarta traffic jam). The most intense storm on record was Typhoon Tip which hit the North Western Pacific Ocean in 1979 with sustained wind speeds of up to 310 km/h (190 mph). Tip was also the largest on record covering an area 2,170 kilometres (1,350 miles) in diameter.

In the Southern hemisphere the tropical cyclone season runs from November 1 until the end of April, with peaks in mid-February to early March.

Historically storm surge (rise in sea level) has caused 90% of fatalities from tropical storms.

There are different scales used in different parts of the world to categorise tropical storms.

In Indonesia we use the Australian region tropical cyclone intensity scale although if a tropical storm forms north of 10 degrees south and between 90 degrees and 125 degrees East then it comes under the jurisdiction of the Jakarta, Tropical Cyclone Warning Centre (TCWC) and is called a Tropical Depression. Once it hits 34 knots it is categorised a tropical cyclone and is given a name (I mean a real name and not something like “that fertling wind”).

The Beaufort Scale

The stronger the wind the more damage it can cause (funny that) a fact that was not lost on Ethel Beaufort who, in 1805, was just finishing her entry for the annual Upper Snodsbury church fete rice pudding competition when a strong wind blew up her back passage, in through the kitchen door and removed the skin. Now a rice pudding without a skin is no laughing matter. Little boys the length and breadth of the British Isles have, for generations, fought with their siblings for the skin of the rice pudding. Gastronomic experts across the globe who have mastered the subtlety of English cuisine fully understand the importance of the rice pudding skin and the culinary skills required to make it.

Ethel was so disturbed by this event that she carried out a lifelong study on the wind strength required to remove the skin from a rice pudding and developed the Beaufort scale to quantify the effects of different wind speeds. It is a little known fact that the idea was borrowed by her husband, a sailor by the name of Rear Admiral Francis (Pudding Frank to his friends) Beaufort, who used to sail the seven seas with a rice pudding strapped to his binnacle.

Categories of cyclones and hurricanes, wind strengths and damage to be expected

So what can we expect from a Cyclone? Well here’s a bit of a summary:

Tropical Depression (Tropical Low in Australia)

  • Sustained windspeeds 0 to 63 km/h (0 to 34 knots) with gusts from 0 to 9 km/h (49 knots)
  • Beaufort Scale - No effect noted on rice puddings.

Tropical Cyclone category 1 (Tropical storm in the Northern hemisphere)

  • Sustained windspeed 64 to 88 km/h (34 to 47 knots) with gusts from 91 to 124 km/h (50 to 67 knots)
  • Damage to be expected - Minimal
  • Damage mostly restricted to trees, shrubbery and lightweight structures; no substantial damage to other structures; some damage to poorly constructed signs.
  • In coastal areas some road flooding and minor damage to jetties and piers.
  • Beaufort Scale - Ripples observed on the surface of rice puddings.

Tropical Cyclone category 2 (Tropical storm in the Northern hemisphere)

  • Sustained windspeed 89 to 117 km/h (48 to 63 knots) with gusts from 125 to 164 km/h (68 to 89 knots)
  • Damage expected - Moderate
  • Considerable damage to tree and shrubbery foliage, some trees blown down; extensive damage to poorly constructed signs and some damage to windows, doors and roof materials, but no major destruction to buildings. Coastal roads and low-lying escape routes inland cut off by rising water about two to four hours before landfall; considerable damage to jetties and piers, marinas flooded; small craft in protected anchorages torn from moorings.
  • Beaufort scale - The skin of the rice pudding starts to lift around the edges.

Severe Tropical Cyclone category 3 (Typhoon or Hurricane category 1 and 2 in the N hemisphere)

  • Sustained windspeed 118 to 159 km/h (64 to 85 knots) with gusts from 165 to 224 km/h (90 to 121 knots)
  • Damage to be expected - Extensive
  • Foliage torn from trees; large trees blown down; poorly constructed signs blown down; some damage to roofing, windows, and doors; some structural damage to small buildings.
  • Serious flooding in coastal areas; many small structures near the coast destroyed; larger coastal structures damaged by battering waves and floating debris.
  • Low-lying escape routes inland cut off by rising water about three to five hours before landfall; flat terrain 1 metre or less above sea level flooded up to 14 or more kilometres inland.
  • Evacuation of low-lying residences near to shorelines may be required.
  • Beaufort scale - The skin is blown off the rice pudding.

Severe Tropical Cyclone category 4 (Typhoon or Hurricane category 3 and 4 in the N hemisphere)

  • Sustained windspeed 160 to 200 km/h (86 to 107 knots) with gusts from 225 to 279 km/h (122 to 151 knots)
  • Damage to be expected - Extreme
  • Shrubs, trees, and all signs blown down; extensive damage to roofs, windows, and doors, with complete failure of roofs on many smaller residences.
  • Flat terrain 3 metres or less above sea level flooded as far as 10 kilometres inland; flooding and battering by waves and floating debris cause major damage to lower floors of structures near the shore; low-lying escape routes inland cut off by rising water about three to five hours before landfall; major erosion of beaches
  • Massive evacuation of residences as far as 10 kilometres inland may be required.
  • Beaufort Scale - The skin is blown off the rice pudding, the rice pudding follows.

Severe Tropical Cyclone category 5 (Super Typhoon or Major Hurricane category 4 or 5 in the N hemisphere)

  • Sustained windspeed of more than 200 km/h (107 knots) with gusts greater than 279 km/h (151 knots)
  • Damage to be expected - Catastrophic
  • Trees, shrubs, and all signs blown down; considerable damage to roofs of buildings, with very severe and extensive damage to windows and doors; complete failure on many roofs of residences and industrial buildings; extensive shattering of glass in windows and doors; complete buildings destroyed; small building overturned or blown away.
  • Major damage to lower floors of all structures less than 5 metres above sea level within 500 metres of the shore.
  • Low-lying escape routes inland cut off by rising water about three to five hours before landfall; major erosion of beaches.
  • Massive evacuation of residential areas on low ground as far inland as 18 kilometres may be required.
  • Beaufort Scale - Rice pudding, bowl, kitchen table and cook have never been found to assess the damage.

Copyright © Phil Wilson 2011
This article or any part of it cannot be copied or reproduced without permission from the copyright owner.

21 December 2017 Copyright © Mr Fixit,
Jl Bypass Ngurah Rai, Gg Penyu No 1, Sanur, Bali 80228, Indonesia
Telephone: +62-361-288-789, Fax:+62-361-284-180