User:Groupstorm08

Year 10 2008 - Geography: Storms
By Cameron Anderson, Hamish Conroy and Sean Shanahan

1)Explain the geographical processes involved in the hazard:

Storms can be defined as many types of storms:


 * Thunderstorms
 * Perfect Storms (when two storms combine)
 * Tornado's
 * Tropical Cyclones (Hurricanes)
 * Extratropical Cyclone
 * Winter storm
 * Blizzard / Ice Storm.

The usual definition of a storm in Sydney would be a thunderstorm while storms in the wet season in Northern Australia would be defined as a Tropical Storm / Cyclone because of the monsoonal troughs coming south in our summer.

What causes severe thunderstorms:

Thunderstorms develop when warm, humid air near the ground receives an initial upward push from converging surface winds and rises rapidly in an unstable atmosphere. Thunderstorms can become severe when the atmosphere is particularly unstable and/or additional energy is drawn in from surrounding winds.

A severe thunderstorm is defined as one which produces:

Hail, diameter of 2 cm or more ($2 coin size) Wind gusts of 90 km/h or greater Flash flooding Tornadoes, or any combination of these.

Most thunderstorms do not reach the level of intensity needed to produce these dangerous phenomena, but they all produce lightning which can cause death, injury and damage.

Lightning and Thunder:

Lightning is the discharge produced when voltage differences between ground and atmospheric electrical charge are large enough (several hundred million volts) to overcome the insulating effect of the air. Strokes can occur within the cloud, between clouds, or between clouds and the ground. Thunder is the sound produced by the explosive expansion of air heated by the lightning stroke to temperatures as high as 30,000°C.

Hail

Hailstones can form in a thunderstorm with a strong updraught when frozen raindrops, 'suspended' in the updraught, grow rapidly by 'sweeping up' small cloud droplets which freeze on contact. Hailstones larger than cricket balls have been recorded in Australia - one example was the severe thunderstorm in April 1999

Where do severe thunderstorms strike:

Severe thunderstorms can occur at any time of the year, although they are very rare during the dry winter months in the north. Most strike between September and March when the supply of solar energy is greatest, but severe winter storms linked to cold fronts are common in the south-west of Western Australia and south-east South Australia. The geographical spread of severe thunderstorms in Australia is difficult to determine because of our low population density and lack of observations over most of the continent. While records of thunderstorm impact show that the most damaging thunderstorms have occurred in the populous south-east quarter of the continent, analysis of wind, hail and tornado data suggests that severe thunderstorms are a significant threat throughout the country. The most damaging individual thunderstorms have hit south-eastern Queensland and the central NSW coast.

http://i257.photobucket.com/albums/hh222/Groupstorm08/thunder_diag.jpg

http://www.youtube.com/watch?v=KU6bY86jSxY&feature=related

http://www.youtube.com/watch?v=9NDkmqaWcuk&feature=related

2)Discuss the following impacts of the natural hazard:

a)Economic:

With the renowned physical damage that is caused by storms the physical damage also has a strong impact on the economy. Through severe storms many homes and buildings are damaged. This results in a large economic impact. Storms in Australia have their largest economic impact on insurance and the insurance industry.

A key example of this is the hailstorm which occurred in Sydney in April 1999, many thousands of buildings and homes suffered serious roof damage. in fact the insurance losses exceeded 1.7 Billion dollars.

An article in the Australian states that Brian Grieg (The head of KPMG's insurance group) said that "first half results from Australia's top insurers reflected the impact of severe weather events over the past 12 months in Australia and New Zealand". It follows that Western Sydney's pre-Christmas hailstorm alone left an estimated $400 million worth of damage bills. Overall severe storms have been estimated to cost Australia about $284 million per annum.

b)Environmental:

As well as their large impact on the Australian economy and insurance industry, storms also have a large impact on the environment. Storms can cause a very large amount of environmental damage, this is because storms are associated with storm tides, lighting and thunder, hail, tornadoes, water spouts winds and flash flooding. However while storms are renowned for their overall negative impact on society and its environment, storms however have also been needed in some cases. In drought affected areas with a water catchment storms have been known to dramatically increase water levels in catchment areas.

Storms can be very damaging to environments and certain ecosystems in Australia and its bush land. In particular trees are often struck by thunder/lightning, in turn knocking them over and possibly starting fires in the bush. Many severe storms particularly in rural and suburban environments trigger floods which is extremely damaging to crops, wildlife and cattle. Storms can be very damaging to many different environments as they are the only natural disaster that can occur almost anywhere in the country.

An example of how storms can trigger many other natural disasters which affect different environments, is the Fires in 1961 in South Australia. these fires were triggered by a severe storm which was occurring at the time. These fires had severe impacts on the surrounding environment in the bush lands. This would have destroyed many fragile ecosystems.

c)Social:

While there are many notable economic and environmental impacts of severe storms there are also many ways in which severe storms have affected Australia's society. As Australians in particular our lives are heavily impacted by natural disasters and we have had to adapt to this over time, natural disasters have been a part of our society since the British colonization and even further back in the Aborigines and the dreaming. We know these social impacts as they have been recorded in geographical records and in the stories of the aboriginal dreaming, in which there are recurring themes of severe weather and storms.

As Australians and as an evolving society we have changed our lives to better suit our environment. For example many Australians who live in areas which would be affected by storms have prepared them selves in certain ways that would protect themselves and their home in case of a storm.

Australia is unlike any other country in the world in that from north to south and from east to west our country can experience so many different types of weather. Queensland in particular is a perfect example of a part of Australia that has better suited itself to its environment e.g many of the homes in North Queensland are built on stilts to protect themselves from flash flooding triggered by the many severe storms which frequently occur in the area.

3)Analyse the responsibility and responses of individuals, groups and various levels of government to the impact of the natural hazard:

Goverment groups such as the State Emergency Service (SES) have the responsability of responding to the impacts of storms. They help out by helping to prepare for severe storms and helping people who have been severley affected, they do this by supplying food, some forms of shelter and deliver the basic necessities of daily life, like sanitation, power and clean water.

The NSW SES has over 10,000 volunteers who work in 228 locations, they all recieve a few months of basic training so that they can help rescue people in immediately dangerous situations caused by severe storms, such as floods, collapsing buildings, car crashes or people caught in powerful currents.

If storms become seriously dangerous or severe, which could mean flooding or strong winds, evacuation plans are immediately drawn and executed in order to assist the victims of the storm.

Bibliography:
Section 1:


 * http://australiasevereweather.com/storm_news/index.html


 * http://ozthunder.com/chase/chase.html


 * http://www.bom.gov.au/info/thunder/#definition

Section 2:


 * http://www.abs.gov.au/ausstats/abs@.nsf/7d12b0f6763c78caca257061001cc588/fecb2ab6de16171eca2570de0005871b!OpenDocument
 * http://www.bom.gov.au/info/thunder/#impact
 * http://www.theaustralian.news.com.au/story/0,25197,23367983-36418,00.html
 * http://www.abs.gov.au/AUSSTATS/abs@.nsf/7d12b0f6763c78caca257061001cc588/00408ced366bb56aca2570de00029f46!OpenDocument

Section 3:

http://www.emergency.nsw.gov.au/home.html http://www.ses.nsw.gov.au/