Weather KQ3 Flashcards
What are the two key characteristics of tropical cyclones?
Strong winds due to the low central pressure which the difference in pressures create strong winds which causes winds to spiral inwards and upwards at high speed of up to 119km/h. Another key characteristic is an area of low central pressure which is formed in the middle of the tropical cyclone (the eye) which is characterized by calm conditions and the absence of clouds.
Describe and explain the distribution of tropical cyclones.
Tropical cyclones are found between 8-15 degrees North and South of the Equator. This is due to the conditions needed for cyclone formation which are high ocean surface temperatures above 26.5°C and sufficiently high Coriolis hemisphere to cause the winds to rotate.
Describe the hazard associated with tropical cyclones that are storm surges.
A storm surge is a sudden rise of sea levels in which water is piled up against a coastline beyond normal conditions at high tide. It is formed when low eye pressure causes sea level to rise in addition to strong winds pushing water towards the coast, creating huge waves. Storm surges cause extensive coastal flooding and are responsible for 90% of the deaths associated with tropical cyclones. For example, Typhoon Haiyan in 2013 had storm surges from 5-6m above normal tide level in the Philippines which caused widespread devastation in the city of Tacloban with many buildings destroyed, trees knocked over and cars piled up. Also, many people living along the coast were drowned along with many people in the city that had been caught off-guard by the fast-rising water.
Describe the hazard associated with tropical cyclones that is wind damage.
The strong winds that accompany cyclones can destroy infrastructure and buildings, injure people and cause loose debris to fly and hit people and buildings. For example, Typhoon Haiyan in 2013 had sustained wind speeds of over 150 km/h and gusts as high as 30 km/h that destroyed buildings and homes leaving 1.9 million people homeless and more than 6 million people displaced. Also, thousands of trees were uprooted leading to the loss of habitat and effects on wildlife.
Describe the hazard associated with tropical cyclones that is torrential rain.
The large amount of rainfall causes flooding inland and causes rivers to overflow which destroys farmlands and causes huge financial losses to farmers. Additionally, the excess water in the soil can destabilise slopes causing landslides which can cause rivers to flood, destroy homes and roads. For example, during Typhoon Haiyan in 2013, some areas experience up to 280mm of rainfall in under 12 hours. This caused a lot of flooding of rice, corn and sugar cane fields which led to the destruction of 71,000 hectares (ha) of farmland and contributed to an economic loss of about $6 billion dollars.
Explain the physical impacts of tropical cyclones.
Damage to infrastructure such as roads and bridges makes it very hard to transport emergency supplies such as food, medicine, and water. Houses and buildings are also damaged from flooding or high winds which also result in people having to stay in temporary shelters. For example, Typhoon Haiyan in 2013 destroyed the main airport at Tacloban City, washing away many roads, slowing down the delivery of aid to many of the worst affected areas. As a result, 1.9 million people were left homeless by the Typhoon.
Explain the economic impacts of tropical cyclones.
The economic impacts include to cost of repairs and reconstruction of infrastructure and buildings, the loss of income due to inability to work during period of tropical cyclone or damaged roads and also includes the cost of damage to crops, industry and infrastructure destroyed by the storm. For example, Typhoon Haiyan in 2013 had an economic impact of around $6 billion dollars. Also, 6 million workers lost their sources of income and about 71,000 Ha of farmlands were affected by the typhoon.
Explain the social impacts of tropical cyclones.
Social impacts include the disruption of water supply due to burst sewage pipes which will contaminate the water supply as well as damage to infrastructure disrupting supply of fresh water to people. Another impact is the spreading of diseases due to stagnant water, which allows mosquitoes to breed, as well as dirty water, which results in water-borne diseases such as cholera or typhoid fever. Additionally, people are also displaced from their homes due to rising floodwaters. For example, over 7,000 people were killed by Typhoon Haiyan with 1.9 million people being left homeless and having to live in cramped relief shelters. After Typhoon Haiyan in 2013, there were outbreaks of diseases due to the lack of sanitation, food, water, shelter, and medication. Furthermore, there was widespread looting in the city of Tacloban as people broke into shops and warehouses to get needed supplies.
Evaluate the evacuation of people as a response to tropical cyclones.
Governments can evacuate people to cyclone shelters when a tropical storm is approaching. For example, community cyclone shelters in Bangladesh are built near homes of people to protect them from tropical cyclones and provide them a place to live temporarily. As a result, the use of community cyclone shelters has greatly reduced the number of casualties caused by tropical cyclones in Bangladesh. However, in developing countries, it is difficult to warn people, especially those in rural areas of the approaching danger due to lack of communication such as TV, radio, or phones.
Evaluate the provision of emergency aid as a response to tropical cyclones.
Provision of emergency aid by the government, neighbouring countries and non-governmental organisations of clothes, shelter, food, medicine, and money to repair damage to infrastructure. For example, after Typhoon Haiyan hit the Philippines in 2013, the UK government provided affected residents with food packages, shelter, and hygiene kits for up to 800,000 victims. As a result, affected residents are provided with medical aid, food, and shelter immediately following the disaster and with financial aid to help rebuild their homes. However, it may be difficult to get aid into the affected areas due to damage to infrastructure. Also, the amount of aid may not be sufficient to provide for all residents.
Evaluate the mitigation measure that is prediction and warning.
By analysing long-term climate records, scientists can establish the pattern and severity of past cyclones to predict future cyclones. They can also analyse the paths of current cyclones through computer modellingg to establish the likely path the cyclones will take based on weather information to allow people to evacuate on time. For example, Japan and America has advanced prediction and warming systems, which tracks cyclone formation and development. They have also instituted necessary measures to be taken when cyclones are approaching. As a result, these systems allow people to secure their property and evacuate way before tropical cyclones arrive. However, the predicted paths of the cyclones are based on the weather information available and weather conditions may change quickly. Also, the accuracy of the prediction gets more accurate as the cyclone approaches land decreasing the amount of time that people have to evacuate the affected areas.
Evaluate the mitigation measure of land use control?
Governments can regulate the use of land along vulnerable areas of the coast by placing restrictions as how the land can be used. The government can make developers pay higher taxes for use of land to discourage development in those areas and make laws which prohibit building along areas of high storm risk. For example, in the Philippines, after Typhoon Haiyan, the Philippines government mandated a no-dwelling zone up to 40m from the high-water mark. As a result, land that is vulnerable to tropical cyclones are used only for recreation and can act as buffer zones against storm surges which will minimise the damage done to property and lives lost. However, land use controls are only successful if properly enforced. Squatter settlements in developing countries are built in such areas due to poor enforcement. Also, some buildings and settlements pre-date land use controls and people may be reluctant to move. Hence, it will be costly for governments to acquire property in these areas to convert them into recreational areas.
Evaluate the mitigation measure of floodplain management.
Floodplain management refers to a master plan to reduce the flood damage potential by mapping risk levels of areas. This allows planners to ensure new developments on flood plains are not prone to flooding, reduce flood damage potential in already developed floodplains and ensure people are able to be evacuated quickly during floods. Also, the construction of storm water drains and pumps to quickly divert water away from urban areas. For example, the Cairns Regional Council, Queensland, Australia has a floodplain management plan based on models of storm surges. The plan shows areas of highest, high and moderate risk of flooding and indicates the primary evacuation routes for residents to take in case of an approaching cyclones. As a result, during Cyclone Yasi in 2011, the flooding in the Central Business District of Carns was limited and damage to property was reduced due to the storm water drains. However, the construction of storm water drains are expensive and many developing countries cannot afford to build them. Additionally, the storm water drains may not be able to cope, and flooding may still occur.
Evaluate the mitigation measure that is reducing vulnerability of infrastructure.
Making infrastructure less vulnerable to the hazards associated with cyclones, such as strong winds and storm surges. This can be achieved by making wind and water-resistant buildings such as using galvanised steel hurricane ties that are nailed to roof to secure it preventing it from being blown off during typhoons and adding secondary water resistant layers to roof to prevent leaking should roofs be blown off. Also, by creating protective barriers along river embankments and coastal dykes to prevent water from overflowing river banks and prevent surging waves from moving inland. Additionally, utility lines for power, telecommunications and water supply can be placed underground to avoid them being damaged by strong winds to ensure services are maintained during the emergency. As a result, effectiveness seen in when houses with these improvements in Florida, USA, survived Hurricane Wilma with little damage in 2005. Contruction of a protective barrier along the coast of Apia, Samoa, protected the coastline and harbour when it was hit by a cyclone in 1991. Without the barrier in 1990, the harbour was destroyed by a previous cyclone. However, reinforcing roofs and houses can be very costly and many developing countries do not have the resources to accomplish this. Also, regular inspection against erosion and expensive maintenance are needed for protective barrier measures to be effective.
