Millionaire cities: Cities with a million people or just over
- In 1950 there were 83 millionaire cities
- In 1997 there were 285
- In 2005 there were 336
Mega cities: Cities with over 10 million people, population density of over 2,000 per km^2
- Most in developed world 1980's
- By 1995 25% of worlds mega cities were in developed world
- In 2003 just 4% of the worlds population lived in mega cities
World cities: A world city dominates beyond it's national border: LONDON. A city that acts as a major centre for:
- Finance
- Trade and business
- Politics
- Culture
- Science
- Information gathering
- Publishing and mass media
- Retail
Cool temperate western maritime
- 4 seasons; coldest in winter, hotter in summer and then cools down through autumn
- 5' in January and 20' in August
- Winds are mostly warm south westerlies, cold north winds are also common
- High rainfall all year round
There are five main air masses that affect the UK
- Artic maritime: forms over the Artic ocean, brings very cold and wet air
- Polar continental: forms over Siberia, brings cold dry air, can bring snow if the air picks up moisture from the North Sea
- Tropical continental: forms over Africa, brings warm, dry air
- Tropical maritime: forms over Atlantic ocean, brings warm wet air
- Polar maritime: forms over North Atlantic ocean, brings cold, wet air
Depressions
- LOW PRESSURE SYSTEM often below 1,000 mb
- A depression is an area of relatively low atmospheric pressure and is recognised on a weather map by a system of closed isobars with pressure decreasing towards the centre
- Isobars will be close together producing a steep pressure gradient, creating strong winds that flow anticlockwise
- Most depressions that affect the UK form over the Atlantic Ocean where the two air masses polar maritime and tropical maritime meet, where cold dense air meets warm light air
- At the polar front the warm air rises above the cooler dense air and as it does this condensation occurs resulting in a band of clouds and precipitation along the front
- Can occur all throughout the year
Anticyclones
- HIGH PRESSURE SYSTEM
- Represented on a weather map by a closed system with pressure increasing on isobars towards the centre
- Move slowly and remain stationary over an area for days or even weeks
- The air in an anticyclone subsides, warming as it falls, producing a decrease in humidity and a lack of cloud and dry conditions
- Winds are weak and flow gently in a clockwise direction in northern hemisphere and anticlockwise in the southern hemisphere
- In winter: cold daytime temps, very cold nighttime temps, clear skies some radiation fogs
- In summer: hot daytime temps, warm nighttime temps, clear skies, morning mists, thunderstorms may occur
29th August 2005
Hit the South-East coast USA
strengthened from a cat 1 to a cat 5
Social Impacts
- 1836 killed
- 300,000 homes destroyed
- 3 million people without electricity
- Bridges collapsed
- Water supplies damages, 5 dead from waterbourne diseases
- 18 schools in New Orleans destroyed
Economic Impacts
- 230,000 jobs lost
- Total damage $300 billion
- 30 oil platform in Gulf of Mexico destroyed
- Many ports damaged, disrupting the shipping industry
Environmental Impacts
- Sea turtle breeding beaches damaged
- Flooding caused oil spills
- Flooding of salt marshes caused loss of habitat
Responses before:
- National Hurricane Centre tracks and predicts hurricanes
- 26th August, NHC issued a hurricane warning
Responses during/after
- Emergency centres set up
- Coastguard, police, fire and army rescued 50,000
- Charities collected $4 billion
Criticisms
-Emergency shelters weren't properly prepared
-Wide spread looting in New Orleans
-Not enough transport to help Evacuate
2nd May 2008
Hit Burma
Strengthened to a cat 4
215km/h winds and 5m storm surge
Social Impacts
- 140,000 killed at least
- 450,000 homes destroyed
- 4000 schools destroyed
- 205 million people homeless
- 70% had no access to clean water
Economic Impacts
- 600,000 hectares of agricultural land damaged
- 200,000 farm animals killed
- 40% of food stores destroyed
- Cost $4 billion
Environmental impacts
- 38,000 hectares of mangrove forests destroyed
- flooding caused erosion and salination of the land
Not prepared?
- Doesn't have a dedicated hurricane monitoring centre
- India warned Burma 48 hours prior, not enough was done
- Warnings had been given on TV and Radio, lots of population do not own these
- No-one knew where to evacuate to
Slow response?
- Refused foreign aid initially
- Ships with aid were refused entry due to fear of war ships
- 19th May aid workers were allowed in
1987 Storm – Case Study
15th of October 1987
Occurrence
- October 1987 started off fine and dry but quickly became
unsettled and wet. In the days before the storm low pressure
lingered off the west of Ireland, producing spells of wet weather
across Britain.
- Warm air from Africa met cold air from the Atlantic Ocean, causing an intense depression
- The depression developed over the Bay of Biscay on 15th October and moved northwards
- Weather forecasters thought it wouldn’t reach England, but by
midnight it had changed course and moved towards the south coast –
most people went to bed
without knowing that there would be very severe winds overnight.
- It was in fact not a hurricane, but a depression.
- Winds were over 100 km/hour and on the coast in
- Hampshire, Sussex and Kent winds reached gale force 11
- There were rapid changes in temperature as the warm front
passed over eg. in Farnborough 8.5°C to 17.6°C in 20 minutes.
- By 9am the storm had passed over land and reached the North Sea
Impact
- Winds gusting at up to 100mph
- 18 people killed in England
- 15 million trees were blown down, including 6 of the famous oaks trees in Sevenoaks, some areas lost 97% of their trees, causing a loss of habitat
- Many fell on to roads and railways, causing major transport delays
- Others took down electricity and telephone lines, leaving hundreds of thousands of homes without electricity.
- A Channel ferry was blown ashore near Folkestone
- Numerous small boats were wrecked or blown away, with one ship
at Dover being blown over and a Channel ferry was blown ashore near
Folkestone.
- 4 lives in France were claimed
- Trees blocked roads and railways
- Power lines were taken down
- Caravan parks were wrecked
- Falling masonry and trees damaged and destroyed cars and houses
- Fire brigade had 6000 calls in 24 hours
- Buildings collapsed
- A cross-channel ferry, the MV Hengist, beached at Folkestone
- A ship capsized at Dover
- Cost £15 billion in insurance claims, so premiums went up for everyone next year
- Fallen trees provided new habitats for some animals
- Some plants benefited as there was more light on the forest floor allowing them to grow
Response
- During the evening of 15 October, radio and TV forecasts
mentioned strong winds but indicated heavy rain would be the main
feature, rather than strong wind. By the time most people went to
bed, exceptionally strong winds hadn’t been mentioned in national
radio and TV weather broadcasts.
- Warnings of severe weather had been issued, however, to various
agencies and emergency authorities, including the London Fire
Brigade.
- Perhaps the most important warning was issued by the Met Office
to the Ministry of Defence at 0135 UTC, 16 October. It warned that
the anticipated consequences of the storm were such that civil
authorities might need to call on assistance from the military.
- A great deal of effort and money was put into the post-storm clean-up of forests and wooded areas.
- A few people, such as the writer Oliver Rackham and the charity
Common Ground, were active in trying to prevent unnecessary
destruction of trees which, although fallen, were still living.
- Most household policies cover storm damage, and thousands of homeowners have already started claims.
- Based on the findings of an internal Met Office enquiry,
scrutinised by two independent assessors, various improvements were
made. For example, observational coverage of the atmosphere over
the ocean to the south and west of the UK was improved by
increasing the quality and quantity of observations from ships,
aircraft, buoys and satellites, while refinements were made to the
computer models used in forecasting.
STRESS EXCEEDS STRENGTH
- Earthquakes are causes by the tension that builds up at all three types of plate margins
- When these plates move past each other it sends out seismic waves, these vibrations are the earthquake
- The seismic waves spread out from the focus (the place in the atmosphere where the earthquake starts)
- The epicentre is the point on the Earth's surface where the earthquake is first felt (straight above the focus)
Other causes of earthquakes:
- Reactivation of old fault lines
- Subsidence as a result of deep mining
- Pressure on surface rocks from water in large reservoirs
There are three types of seismic waves:
- P waves: can travel through solids and liquids, fastest, push and pull.
- S waves: can travel through only solids, waves move the earth at 90' to the direction of travel.
- Surface waves: Travel near the earths crust in either Love waves, through liquids and solids, side to side, or Rayleigh waves, through liquids and solids in a rolling motion
Measurements:
- Richter scale: measures the magnitude of an earthquake, 1-9+
- Mercalli scale: measures the impacts of an earthquake, 1-12
