3.1.1.3 Weather hazards - Tropical Storms

Question 1

What is the difference between typhoons, hurricanes and cyclones?

Answer 1

• no difference - all names for tropical storms
• Typhoons = South East Asia
• Hurricanes = North/South America
• Cyclones – Indian Ocean

Question 2

What is the global distribution of tropical storms?

Answer 2

tropical storms are formed in the Tropics to the north and south of the equator

Question 3

Where do tropical storms form?

Answer 3

• tropical storms form over warm oceans where the temperature exceeds 27 degrees C - explains why they are found over tropical oceans
• no tropical storms form in South Atlantic and South Pacific due to presence of cold ocean currents in these regions
• most tropical storms form 5-15 degrees N and S of the Equator where there is sufficient ‘spin’ caused by the Earth’s rotation
• at the Equator the effect of the Earth’’s rotation (Coriolis effect) is 0 - explains why tropical storms are not found here
• in tropical regions the intense heat makes the air unstable, causing it to rise rapidly

Question 4

When do tropical storms form?

Answer 4

tropical storms form in the summer and autumn months when sea temperatures are at their highest

Question 5

How does global atmospheric circulation affect tropical storms?

Answer 5

• unstable rising air in equatorial regions (where 2 Hadley cells converge) provides ideal conditions for the formation of tropical storms, encouraging air to rise, condense and form storm clouds
• trade winds are responsible for the predominantly east-west storm paths
  
  • these winds are caused by air-flowing over the Earth’s surface from the sub-tropical high-pressure belts to the equatorial low-pressure belt

Question 6

Explain the distribution of tropical storms:

Answer 6

• They form over warm tropical seas where temperatures are over 26.5/27 °C, usually in late summer and autumn when sea temperatures are at their highest
• They form 5 - 15 °C N and S of the Equator where the characteristic spin can develop – this is due to the rotation of the Earth (Coriolis Force) – any nearer and the spin is not enough
• Slight differences in air masses in the tropics and heating near the surface lead to the air being unstable and rising.
• Air over the oceans contains a lot of water vapour due to the high temperatures. As a result, when the air rises, it cools and condenses, releasing the stored energy – the latent heat
  
  • This powers the hurricane and as more and more water is evaporated, the storm gets bigger and stronger

Question 7

How may tropical storms be affected by climate change?

Answer 7

in the Tropics average temperatures have increased by 0.7 - 0.8 degrees C in the last 100 years

Question 8

Distribution of tropical storms:

Answer 8

where the tropical storms are formed and where they move to

Question 9

Frequency of tropical storms:

Answer 9

refers to the number of tropical storms

Question 10

Intensity of tropical storms:

Answer 10

• how much power the tropical storm has e.g. wind speed
• measured using scale of 1-5
• Category 1 is lowest intensity and Category 5 is highest

Question 11

By how much have sea surface temperatures increased by in recent decades?

Answer 11

0.25 - 0.5 degrees C

Question 12

How might the distribution of tropical storms be affected by climate change?

Answer 12

• as sea surface temps are rising in areas where tropical storms are not usually active - tropical storms could potentially form in the areas in the future
  
  • the seas may be warm enough to provide enough energy to form a tropical storm
• locations of tropical storms may increase as warmer seas mean that the source areas may extend further N and S of equator
• low-lying coastal communities within the tropics are most vulnerable esp. where the population density is high and income level is low
• increase in GHGs may affect distribution of tropical storms scientists have little evidence of a cause and effect relationship

Question 13

How might the frequency of tropical storms be affected by climate change?

Answer 13

• little evidence that number of storms is increasing
• 1980 - 2018 no clear evidence of a change in tropical storms frequency
• lack of historical record for the South Pacific makes prediction about frequency harder
• IPCC concluded that limited evidence that frequency of tropical storms with decrease but there is expected to be an increase in number of very intense storms

Question 14

How might the intensity of tropical storms be affected by climate change?

Answer 14

• increasing evidence that intensity of tropical storms had increased in recent years as a result of climate change
  
  • increase in number of Category 4 and 5 hurricanes likely in the future
  • wind speeds of average tropicals storms projected to increase by up to 10% in future
• warmer, moist rising air provides extra energy for tropical storm formation
• rising sea levels means that risk of coastal flooding from storm surges will be greater
• scientists cautious in identifying a casual relationship until more data is available
• IPCC medium confidence in projecting an increase in heavy rainfall associated with tropical storms if average global temps increase by 2 degrees C

Question 15

When was Hurricane Catarina formed and where did it hit?

Answer 15

2004 Hurricane Catarina hit SE coast of Brazil - which had never been struck by a tropical storm before

Question 16

What allowed Hurricane Catarina to form where it did?

Answer 16

• sea surface temps were higher than average meaning this tropical storm was able to form in the South Atlantic
• with sea surface temps rising in majority of places the locations that tropical storms typically develop in may expand to other regions

Question 17

What category was Hurricane Catarina?

Answer 17

Category 2

Question 18

What was the cost of the total damages from Hurricane Catarina?

Answer 18

$350bn

Question 19

How many homes were damaged and destroyed by Hurricane Catarina?

Answer 19

• 40,000 homes damaged
• 1,500 homes destroyed

Question 20

What % of rice crops were destroyed by Hurricane Catarina?

Answer 20

40% of rice crops destroyed

Question 21

How many people were killed and injured by Hurricane Catarina?

Answer 21

• 3 died
• 75 injured

Question 22

How many people were left homeless by Hurricane Catarina?

Answer 22

2,000 people left homeless

Question 23

Primary effects:

Answer 23

effects that are directly caused by the tropical storm itself

Question 24

Secondary effects:

Answer 24

effects that are a result of primary effects

Question 25

Primary effects of tropical storms:

Answer 25

• storm surge flattening buildings, damaging infrastructure, bringing sea water into land
• crops destroyed
• strong winds destroying buildings, infrastructure etc.
• people drowning in storm surges
• heavy rain causing freshwater flooding
• electricity, water and communications e.g. telephone lines damaged
• fatalities from being trapped under buildings and debris

Question 26

Secondary effects of tropical storms:

Answer 26

• homelessness
• loss of income as people’s livelihoods destroyed
• social disorder or conflicts
• drinking water contaminated
• spread of disease due to unhygienic conditions
• landslides and locked roads, affecting rescue efforts
• trauma, stress and other mental health issues after the event
• food shortages

Question 27

Response:

Answer 27

how the local community, government and international organisations/gov’s react to a hazard so that the effects can be reduced as much as possible

Question 28

Immediate responses:

Answer 28

• actions taken as soon as the hazard happens and in its immediate aftermath
• usually aim to reduce loss of life and provide vital aid resources
• e.g. search and rescue, medical care, food and water, shelters etc.

Question 29

Long-term responses:

Answer 29

• actions taken after the immediate response when the effects of the hazard have been minimised
• aim to restore normality and reduce risk in the future
• e.g. rebuilding infrastructure and homes, cleaning up, building defence mechanisms, setting up warning systems

Question 30

Immediate responses to tropical storms:

Answer 30

• emergency aid for injured people
• financial aid from international gov’s
• providing food and water
• searching for people trapped in damaged buildings or on rooftops (when the flooding has been extreme)
• clearing roads to gain access to isolated areas and allow rescue services entry
• temporary communications set up and emergency power generators in place
• setting up shelters for the homeless

Question 31

Long-term responses to tropical storms:

Answer 31

• clearing debris, landslides etc.
• investments and developments into management e.g. warning systems
• reconstructing infrastructure, schools, ports, hospitals etc. damaged by the storm
• building tropical storm shelters to withstand future storms, as well as more wind resistant homes
• housing reconstruction
• clearing coastal areas of sand brought up by the storms urge
• restoring important industries to boost economy e.g. food production

Question 32

3 ways of reducing the effects of tropical storms:

Answer 32

• monitoring and prediction
• protection
• planning

Question 33

How can monitoring and prediction be used to reduce the effects of tropical storms?

Answer 33

• satellites, radar (using radio signals) and weather charts used to identify the development and movement of tropical storms
• computer programs analyse the data and predict the track of a storm and its likely impacts
• local authorities and emergency services issue warnings and if necessary evacuate people to a safer ground

Question 34

What are the levels of warning in North America used in monitoring and prediction of tropical storms?

Answer 34

• Hurricane Watch - issued across a wide area, advising that hurricane conditions are possible
• Hurricane Warning - more focused on a specific area, advises that people should take immediate action e.g. evacuate

Question 35

How do you forecast a tropical storm

Answer 35

• The weather forecast should relate to the satellite image, so expect reference to the typical sequence of weather conditions associated with the passage of a tropical storm
• Credit any aspects of weather that might realistically occur in the next 24 hours, e.g. cloud cover, precipitation, wind speed and direction, air pressure, humidity, general weather conditions
• Cloud cover will increase over the next few hours and wind speed will pick up dramatically as the outer part of the vortex approaches
• Winds, which will be blowing from the east, may be damaging and there will be torrential downpours of rainfall from dark cumulonimbus clouds
• There is a possibility of tornadoes and thunderstorms with lightning
• A storm surge combined with the heavy rain may cause dangerous flooding in low-lying coastal areas
• Air pressure will drop rapidly
• This will be followed by the centre of the storm or ‘eye’, which will only last for a short time
• The weather is likely to be fairly calm with only light winds and fair weather
• The winds will again increase suddenly as the second part of the vortex approaches
• This will be accompanied by powerful winds blowing from the west, with further heavy rain
• Air pressure will rise as the storm continues northwards, and cloud cover will then become thinner, with more moderate winds
• Eventually the rain will cease, although further belts of showers will occur as the storm moves away

Question 36

How can protection be used to reduce the effects of tropical storms?

Answer 36

• windows, doors and roofs reinforced to strengthen buildings to withstand strong winds
• storm drains constructed in urban areas to take away excessive amounts of rainfall and prevent flooding
• sea walls built to protect key properties from storm surges
• houses close to the coast constructed ons tilts so that a storms urge will path beneath

Question 37

How has protection against tropicals storms in Bangladesh been used?

Answer 37

in Bangladesh 2,500 cyclone shelters have been built along the country’s 710km coast to provide safety for coastal communities

Question 38

Hazard mapping of tropical storms:

Answer 38

• identifying the areas most at risk and taking action
• ensuring important buildings built away from high-risk areas

Question 39

Evacuation routes and safety protocols:

Answer 39

• creating evacuation routes and developing warning systems ensure the population is prepared for a storm and will be alerted when one is coming
• e.g. hurricane sirens signal to people that they must take shelter

Question 40

Raising awareness to tropical storms:

Answer 40

• raise individual and community awareness about potential dangers and how to respond to tropical storms
• can lower their risk by planning in advance - getting important supplies, organising documents, being aware of their local shelter