Natural Hazards affecting Australian Communities
Tables of contents-
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Table of contents
Q1, Q2, Q3
Natural hazards affecting Australian communities- Cyclones
Q1.identify the type of natural hazard you have selected.
The natural hazard that I have selected is Cyclone also known as Hurricanes in the USA and typhoon in Asia.
Q2. Describe in detail the physical geographical process associated with the hazard.
Firstly in order for a cyclone to happen you will need very specific requirements including:
Sustained wind speeds of more than 120 km/h surrounding the centre
Very low atmospheric pressure system and
Increase sea level, storm surge and wave heights
Also most cyclones will have:
Eye diameters of 40 km on average
Eye wall marks the strongest wind and heaviest rainfall and
Spiral rain band clouds that extend over 1000 km from the eye
A cyclone needs a water temperature of 26.5 degrees Celsius for it to form. However once the cyclone is produced the water temperature will no matter as much only that more favourable water temperature means a longer lasting and persisting cyclones. They occur in areas of very low pressure when air that is heated by the sun rises rapidly, heating up water into thunderstorm clouds. They later clump together to make the bases for the cyclone.
The hot air then rises above leaving only the cold air underneath. Therefore this creates a low pressure system which is the next requirement for a cyclone. The Coriolis Effect of the Earth spins on its axis therefore creating a force which carries the cyclone on its path. This causes the winds to rotate faster which causes the low pressure system to increase in its intensity into a tropical depression which will later on turn into a tropical cyclone that can cause immense amounts of damage to the affected areas. Also cyclones have a clear and calm centre called the 'eye'.
Q3. Describe the duration and intensity of the natural hazard.
The duration of a cyclone is determined by the atmospheric environment, movement and sea surface temperatures. Most cyclones last between 3-8 days while some weak ones reach gale force speeds quickly others such as Hurricane Ginger in 1971 lasted for more than 30 days. This was due to it being in favourable conditions during that time. The longest lasting most intense cyclone was hurricane Ivan in 2004. It lasted 7 days but is estimated to have speeds of at least 200 km/h.
Cyclones intensity is defined by the maximum mean wind speed over flat land or water. The wind speeds in a cyclone are the most strongest around 25 km from the centre with the centre having the weakest wind speeds. The Beaufort scale is used to find and classify wind speeds to hurricanes using the average wind speed, estimated speed over land and estimated speed...