Weather and climate (KQ3) Flashcards

1
Q

What is a tropical cyclone?

A
  • weather systems that develop over the warm oceans in the tropics
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2
Q

What are the characteristics of tropical cyclones?

A
  • strong winds
  • low central pressure
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3
Q

How are strong winds formed?

A
  • the atmospheric pressure just above the warm oceanic surface in the centre of the cyclone is very low
  • the steep pressure gradient results in strong winds spiralling inwards and upwards at high speeds
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4
Q

Where is low pressure found?

A
  • formed at the eye
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5
Q

How is the low pressure formed?

A
  • moist, warm air over the ocean expands and rises
  • as warm air rises, condensation occurs
  • releases latent heat
  • latent heat is heat energy releases when water vapour condenses into water droplets
  • the continuous large-scale release of latent heat warms the air, causing air to expand and rise further
  • this reduces air pressure near the ocean surface, creating an area of low pressure in the centre of the cyclone
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6
Q

How is the eye formed?

A
  • as warm air rises, it cools and sinks
  • the descending dry air creats an environment at the centre of the cyclone
  • the centre is characterised by its calmness and absence of clouds
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7
Q

Where are tropical cyclones formed?

A
  • most develop between latitudes of 8 and 15 degrees north and south of the equator
  • but not close to the equator
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8
Q

What are the weather conditions needed for a tropical cyclone to form?

A
  • warm waters (above 26.5 degrees celsius)
  • coriolis effect
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9
Q

Why are warm waters needed for a tropical cyclone to form?

A
  • heat and moisture from the ocean are required for the tropical cyclone to form
  • when they travel over land or cool waters, they are unable to sustain their energy and dissipate
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10
Q

What are tropical cyclones also known as?

A
  • hurricanes
  • typhoons
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11
Q

Why is the presence of the coriolis effect needed for tropical cyclones to form?

A
  • the strong pressure gradient causes air to move straight inwards to the cyclone
  • however, the coriolis effect causes air to move at an angle instead
  • the coriolis effect is needed to begin the rotary motions of cyclones
  • tropical cyclones do not form within 5 degrees north and south of the equator due to weak coriolis effect
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12
Q

What happens to tropical cyclones in the northern hemisphere and why?

A
  • they rotate in an anti-clockwise direction
  • due to the coriolis effect deflecting winds to the right
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13
Q

What happens to tropical cyclones in the southern hemisphere and why?

A
  • they rotate in a clockwise direction
  • due to coriolis effect delfecting winds to the left
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14
Q

What are the hazards associated with tropical cyclones?

A
  • storm surges
  • strong winds
  • torrential rain
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15
Q

What are storm surges?

A
  • sudden rise of sea level in which water is piled up against a coastline
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16
Q

What are storm surges caused by?

A
  • low air pressure
  • strong winds
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17
Q

How are storm surges formed?

A
  • when a tropical cyclone forms over warm waters, the intense low pressure in the eye causes sea levels to rise
  • strong winds push the water towards the coast and creates huge waves
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18
Q

What are the damages caused by tropical cyclones?

A
  • they cause the greatest amount of damage to coastal areas
  • massive flooding can destroy property and cause high death tolls
  • storm surges may also result in boats (vessels) being swept in from the coast and stranded inland
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19
Q

What is an example of a tropical cyclone and what damage did it cause?

A
  • hurricane ike (Texas)
  • caused storm surge of between 4 and 6 metres above normal tide level
  • estimated property damage: US$24.9 billion
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20
Q

What are strong winds?

A
  • the strong forces of the winds that accompany tropical cyclone
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21
Q

Why do strong winds cause damage?

A
  • they can destroy or damage infrastructure as well as injure people
  • the winds can cause loose debris to fly and hit people and buildings
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22
Q

What is an example of a tropical cyclone with strong winds?

A
  • Hurricane Andrew
  • 1992
  • attained strong wind speeds of up to 177km/h
  • caused widespread damage to the bahamas and various parts of the USA
  • damage to infrastructure disrupted power supply and left about 150000 homes without electricity
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23
Q

What causes torrential rain?

A
  • tropical cyclones produce large amounts of rainfall that can result in inland flooding
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24
Q

How does torrential rain cause flooding?

A
  • the sudden and large amount of rainfall adds to the flow of water in rivers and streams
  • causes them to overflow (flooding)
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25
Q

How does torrential rain cause damage and what damage does it cause?

A
  • heavy rainfall may destabilise slopes
  • this is due to too much water being in the soil causing it to be unstable
  • this can lead to a landslide
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26
Q

What damage do landslides cause?

A
  • they can entirely remove or crush buildings
27
Q

What is an example of a tropical cyclone with torrential rain?

A
  • Hurricane isabel
  • 2003
  • flooded rivers that flowed across Virginia, maryland, Delaware and Washington D.C
  • damage of more than US$2.23 billion
28
Q

What are the 3 categories of impact of tropical cyclones?

A
  • physical impacts
  • economic impacts
  • social impacts
29
Q

What do physical impacts refer to?

A
  • the hazards associated with tropical cyclones can cause damage to infrastructure (buildings, bridges and roads)
30
Q

What happens when bridges and roads are destroyed?

A
  • becomes difficult to transport food, clean water and medicine to places in need
  • communication networks disrupted
31
Q

What is an example of a tropical cyclone with physical impacts?

A
  • Typhoon Ketsuna
  • 2009
  • caused serious damage to road networks in Philippines, cambodia and Laos
  • this hindered rescue work
  • 80% of health centres in Manila were destroyed by the tropical cyclone
  • it was difficult to distribute food and medicine to those in need
32
Q

What do economic impacts of tropical cyclones include?

A
  • cost of repairs of damaged property and infrastructure
  • loss of income due to damaged crops (yasi bananas)
33
Q

What was a tropical cyclone with economic impacts of cost of repairs of damaged property and infrastructure?

A
  • Hurricane Katrina
  • 2005
  • struck the east coast of the USA
  • estimated cost of damage: US$81 billion
34
Q

What was a tropical cyclone with economic impacts due to damaged crops?

A
  • Tropical cyclone Yasi
  • 2011
  • In North Queensland, Australia
  • 75% of the total banana crop lost
  • amounted to $350 million
  • sugar cane farmers also suffered a loss
  • cyclone destroyed 20% of total area of farmland
35
Q

What do social impacts of tropical cyclones include?

A
  • disruptions to water supply and sanitation and hygiene facilities
36
Q

Why are people in affected areas unable to get fresh water?

A
  • physical damage to infrastructure caused by tropical cyclones causes water pipes and pumps to be damaged
37
Q

How to existing water supplies get contaminated during a tropical cyclone?

A
  • flooding causes sewage from burst sewage pipes to flow into existing water supplied, contaminating them
38
Q

What are the consequences of consumption of contaminated water?

A
  • spread of water-borne diseases
  • e.g. cholera, typhoid fever
39
Q

What was an example of a tropical cyclone that caused the spread of water borne diseases?

A
  • Cyclone Alia
  • 2009
  • West Bengal India
  • contaminated drinking water caused a cholera outbreak
  • 1000 infected, 14 deaths
40
Q

What else can flooding due to tropical cyclones cause?

A
  • spread of diseases transmitted by insects
41
Q

What is an example of a tropical cyclone that caused the spread of a disease transmitted by insects?

A
  • Hurricane Mitch
  • 1998
  • Guatemala and Nicaragua
  • in most cases, the large-scale flooding and the rapid spread of diseases make in difficult to provide adequate healthcare
42
Q

What is another social impact of tropical cyclones?

A
  • displacement of people from their homes
43
Q

What is an example of a tropical cyclone that displaced people from their homes?

A
  • Hurricane katrina
  • 2005
  • New Orleans, USA
  • hundreds of thousands of people lost their homes
44
Q

What are the 2 categories of responses of tropical cyclones?

A
  • emergency action
  • mitigation measures
45
Q

What does emergency action refer to?

A
  • taking immediate action to respond to a situation that threatens people’s lives and health
46
Q

What is done to minimise injury and deaths when tropical cyclone strikes?

A
  • governments may issue weather warnings and advisories to people
  • a cyclone proof place e.g. a community cyclone shelter may be built close to homes of people in areas prone to tropical cyclones
47
Q

How do government issued weather warnings and advisories minimise death and injury when a tropical cyclone strikes?

A
  • they have enough time to make preparations to protect their lives and property
  • minimises death and injury when a tropical cyclone strikes
48
Q

How do cyclone-proof places minimise death and injury when a tropical cyclone strikes?

A
  • a tropical cyclone shelter is built with strong concrete, which is raised above the ground to withstand the hazards to do with tropical cyclones
  • people can be evacuated to the shelter easily before the cyclone strikes
49
Q

What are the successes of emergency action?

A
  • countries such as Bangladesh and India experience a reduced number of casualties with the use of community cyclone shelters
50
Q

What are the limitations to emergency action?

A
  • emergency action requires assisstance from the national government as well as that of neighbouring countries to help repair infrastructure and provide aid to the victims
  • it also requires NGOs such as red cross, oxfam and save the children to provide relief teams and aid in terms of clothing, food and healthcare to victims living in affected areas
51
Q

What do mitigation measures of tropical cyclones include?

A
  • prediction and warning
  • land use control
  • reducing vulnerability of infrastructure
52
Q

How does prediction and warning work as a mitigation measure?

A
  • long term climate records of a country prone to tropical cyclones can be analysed to find a pattern of occurence and severity and damage of past cyclones
  • computer modelling can also help to predict the path of a cyclone and the extent of its damage
53
Q

How does knowing the pattern of occurence of a tropical cyclone help minimise the extent of its damage?

A
  • the pattern of occurence of tropical cyclones allows relevant authorities to predict when a cyclone of similar severity would occur, minimising death and injury and the extent of damage
54
Q

What are some successes of prediction and warning as a mitigation measure to tropical cyclones?

A
  • Japan and USA
  • use warning systems for tropical cyclones to provide information on the severity of tropical cyclones and advise the public to take the necessary precautionary measures beofre a cyclone strikes
55
Q

What are the limitations to using prediction and warning as a mitigation measure to tropical cyclones?

A
  • climate records of past events only indicate the frequency of tropical cyclones, they do not provide details on the occurence of future tropical cyclones
  • the prediction on the cyclones path may be innaccurate as it is based on weather information available at a particular point in time and weather conditions can change quickly
56
Q

What does land use control include?

A
  • coastal plain management
  • floodplain management
57
Q

How does coastal plain management work as a mitigation measure in response to tropical cyclones?

A
  • developers may need to pay higher taxes if they want to develop land along the coast, which are prone to strom surges and flooding caused by tropical cyclones
  • by imposing higher taxes, they may be dettered from developing on these vulnerable areas
  • these areas can the be used for recreational purposes such as parks
  • protected zones can be set up to restrict any development so that these areas can be used as a barrier against storm surges and flooding
58
Q

How does floodplain management work as a mitigation measure in response to tropical cyclones?

A
  • a floodplain refers to low-lying areas near rivers or the coast
  • this management is a plan to reduce the potential of flood damage by mapping the land use of an area and implementing necessary actions to prevent flooding
59
Q

What are some successes of land use control as a mitigation measure to tropical cyclones?

A
  • land use control is able to prevent new developments in floodpains prone to floods
  • the implementation of necessary action helps minimise the potential of flood damage in existing developments on the floodplain
  • this management also includes evacuation plans to ensure that people are able to leave a flooded area quickly
60
Q

What are some limitations to land use control as a mitigation measure?

A
  • coastal plain management is successful only if the authorities are able to enforce them as well as have enough manpower and time to carry out the enforcement
  • the land along the coasts may have been developed for a long time. Thus, residents may not be willing to relocate
  • buying land along to coast to convert to recreational areas can incur high cost for the government
61
Q

How does reducing vulnerability of infrastructure work as a mitigation measure in response to tropical cyclones?

A
  • buildings designed with special features to withstand wind and water damage by tropical cyclones
  • river embarkments and coastal dikes are inspected regularly as they can be eroded by river waters and coastal waves
  • these protective barriers are important to reduce the damage caused by storm surges
62
Q

What are some examples of reducing vulnerability of infrastructure as a mitigation measure?

A
  • fitting roofs of buildings with galvanised steel hurricane ties to prevent them from being blown away by strong winds
  • fitting roofs with a layer of secondary wayer resistance to prevent leaking when the roof is blown off
  • building river embarkments which are walls by the sides of rivers to prevent a river from overflowing
  • building coastal dikes which are artificial walls made of stone to prevent flooding on coastal areas
  • placing utility lines such as power and networks of telecommunications underground so they are protected from strong winds and storm surges
63
Q

What are some successes in reducing the vulnerability of infrastructure as a mitigation measure against tropical cyclones?

A
  • the state government of florida (USA) engages the help of specialized companies to improve the design of the roof and opening of houses
  • these measures were successful as many houses on jensen beach only suffered minor roof damage caused by hurricane wilma in 2005
  • a protected barrier was built along the coast of Apia, Samoa after the harbour was destroyed by cyclone ofa in 1990
  • the barrier was successful in protecting the coastline and the harbour as it was not destroyed by cyclone val in 1991
64
Q

What are some limitations of reducing vulnerability of infrastructure as a mitigation measure in response to tropical cyclones?

A
  • it can be expensive to repair and maintain the protective barriers