The challenge of natural hazards Flashcards
TROPICAL STORMS
What are the initial impacts of a tropical storm?
- the initial impact of a tropical storm
- there are 3: strong winds- at least 73mph per hour, torrential rainfall (500mm in 24 hours), storm surges- a rising of the sea as a result of wind and atmospheric pressure.
What are the secondary effects of a tropical storm?
- indirect impacts
- include flooding, landslides and contaminated water sources
What are the immediate responses of a tropical storm?
- evacuation
- shelter provided by public buildings
- distributing emergency food and water
What are the long term responses to a tropical storm?
- repairing damage to existing buildings, infrastructure and businesses
- ensuring the country can manage a future hazard using protection and prediction
When was Typhoon Haiyan?
November 4th, 2013.
Most intense on the 5th November, 6.00pm
Where did Typhoon Haiyan affect?
Hit the Philippines- Haiyan was the 25th tropical storm to enter Filipino waters in 2013
What were the primary effects of Typhoon Haiyan?
- people were killed by flying debris eg corrugated iron roofs- 6,000 deaths in total
- three massive waves destroyed 95% of trees in the region of Eastern Samar
- storm surge at Mangalabang destroyed coral reefs
What were the secondary effects of Typhoon Haiyan?
- destruction of coral reefs meant people were not able to make a living from fishing
- 8 people killed in stampede at a relief centre in a rush to receive food aid
What were the immediate responses to Typhoon Haiyan?
- government issued major typhoon warnings, and evacuated thousands to shelters
- the united nations sent in emergency teams to assess what happened
What were the long term responses to Haiyan
- relocated 1 million people away from coastal danger and the designation of ‘no dwelling zones’
- employment and training provided for those who had a change in livelihoods
How can the effects of tropical storms be reduced through monitoring and prediction?
- can save lives and reduce damage
- Satellites monitor cloud patterns whilst equipped aircrafts collect air pressure, rainfall and wind speed data
How can the effects of tropical storms be reduced through protection and planning?
- mitigation= involves the modification of homes and infrastructure
- planning involves educating people
THE UK’S CHANGING WEATHER
What is extreme weather?
-weather that is extremely different to the usual weather pattern e.g a blizzard
What types of weather hazard does the UK experience
- hydro-meteorological hazards such as storms, flooding
Depressions can cause great storm damage. What is a depression?
- areas of low atmospheric pressure which produce cloudy, rainy and windy weather. They are responsible for the UK’s changing weather
What types of flood hazard affect people in the UK?
- coastal flooding: a deep depression brings a storm surge to a major river estuary, strong winds funnel coastal water into the mouth.
- surface water flooding= intense rainfall collects in hollows and depressions where homes are located
What is a drought?
- an extended period of low or absent rainfall relative to the expected average for a region
- in the UK, 15 consecutive days with below 0.2mm
- Two types, meteorological and hydrological
What are the impacts of extreme cold?
- fatal to crops and cattle
- lead to disruption, In January 2014, 17,000 trains were cancelled
when did the UK experience an extreme weather event?
From 17th to 21st of June 2017- a heatwave, temps exceeding 28 degrees
Where was affected by the heatwave?
-Heathrow in greater London 34.5 degrees
What caused the heatwave?
- high pressure centred to the East of the UK drew a flow of hot air from the near continent to the South
- hot weather also came up Europe
What were the social impacts of the heatwave?
- some people die from swimming in dangerous areas
- increased vulnerability of heat stress e.g the elderly
- very high pollen count
What were the environmental impacts of the heatwave?
- high ozone levels brought toxic air from industrial parts of France on a Southerly wind
- ozone levels reached 200 mg
What were the economic impacts of the heatwave?
- speed restrictions introduced on railway tracks
- roads also melted which the council had to fix
- rise in domestic holidays
What were the management strategies to reduce the risk of heatwaves?
- media issued advice to NHS including shutting windows and pulling down the shades
- people advised to stay out of the sun 11.00-15.00 and asked to check vulnerable neighbours and relatives
What is the evidence that UK weather is becoming more extreme?
-increasing extreme weather, heatwaves in Summer, storms in Winter since 1950
TROPICAL STORMS CONTINUED
What is the global distribution of tropical storms?
- Hurricanes, typhoons, cyclones form in the Tropics between 5 and 23.5 degrees of the equator
- do not form along equator as Coriolis force is not strong enough
What is needed for a tropical storm to form?
- warm ocean temps, 26-27 degrees
- depth of 60-70m
- Coriolis effect
How does a tropical storm form?
- moist air heated and evaporates, creating areas of low pressure
- Strong winds form as rising air draws up more moisture
- Winds start to spin due to Coriolis effect
- rising air condenses and forms cumulonimbus clouds and rain
What happens when a tropical storm approaches land?
- loses energy because there is no longer a supply of warm water
- slows down because of friction
What are the features of a tropical storm?
- circular in shape
- winds spiral round the centre called the eye
- the eye is surrounded by the eye wall
What is the structure of a tropical storm?
- at the start, temps and air pressure fall
- air rises and clouds begin to form
- cumulonimbus clouds form and there is heavy rain
- when the eye passes, there is a period of calm
- sun appears and there is high pressure
- wind and heavy rain increase dramatically again
What are the conditions like in the eye of the storm and why?
-calm, gentle winds and clear skies because cold air sinking, creating areas of high pressure
Why do tropical storms spin?
-Coriolis effect (rotation of the earth)
winds bend due to them blowing from high to low pressure as the earth rotates
What direction do tropical storms spin in?
- in the Northern hemisphere they bend to the right which causes the clouds to swirl anti-clockwise
- cyclones in the Southern hemisphere swirl in a clockwise direction
How is a tropical storm measured?
-on the Saffir-Simpson scale between 1 and 5
How might climate change affect the distribution of tropical storms?
- as ocean temps exceed 30 degrees the intensity of tropical storms will increase
- more tropical storms will reach category 4 and 5
- they may occur more north and south of the tropics
What is global atmospheric circulation?
-a system of winds that transfer heat energy via circulation cells
What is low air pressure?
-rising air that causes unstable atmospheric conditions e.g rainfall, cumulonimbus clouds
What is high air pressure?
-sinking air that causes stable atmospheric conditions e.g clear skies
What causes differences in air pressure?
-differences in temperature
What are pressure belts?
-areas of high or low pressure
What are surface winds?
- winds on the earth’s surface that occur as air moves from high to low pressure
- they transfer heat and moisture and bend due to the Coriolis effect
Why does the sun not heat the earth evenly?
- the earth is spherical and curved
- at low latitudes the sun’s insolation is highly concentrated
- at high latitudes, e.g the Poles, the sun’s rays strike at an angle and are spread over a large surface area
What happens at the equator?
- there is a low pressure belt
- air rises, cools and condenses to form cumulonimbus clouds that bring rain
- the air moves North and South, creating the Hadley cell
What happens at 30 degrees North and South of the equator?
- high pressure belt
- air cools and sinks, creating clear skies
- some of the winds travel North and South, creating the Ferrel cell
What happens at 60 degrees North and South of the equator?
- low pressure belt
- warmer surface winds meet colder surface winds from the Poles
- some of the air moves to the Poles, creating the Polar cell
What happens at 90 degrees North and South of the equator?
- high pressure belt
- cool air sinks creating clear skies and precipitations falls mainly as snow
- surface winds move back to the equator
How do ocean currents affect weather?
- currents transfer heat around the Earth
- cold water sinks and warm water takes it’s place
