- Created by: Maria is the best
- Created on: 28-10-17 14:06
How can weather be hazardous?
Weather-->Day to day condition of atmosphere
Global Circluation System
Heat transfered from poles, by ocean currents & wind, keepiing Earth's temp. balanced.
Air rises at equator-creates low pressure (clouds and rain)
At 30 degrees north and south of equator-air sinks-creates high pressure-HIGH=DRY
At equator-sun's rays=CONCENTRATED-->temperature=very HOT
At poles-sun's rays=less concentrated-->temperature=very COLD
What causes extreme of temperature?
THE ALBEDO EFFECT:How much surface reflects/absorbs sun's rays. e.g. Polar ice=HIGH albedo-->reflecting heat-keeps poles cold & Rainforest=LOW albedo-->absorbs heat-keeps it hot
CLOUD COVER:At equator=lots of clouds-->prevents full force of sun's rays getting through-keeps warm weather instead of extremely hot. At 30 degrees-no clouds-->full force gets thorugh-extremely hot weather and temperatures.
OCEAN CURRENTS:Ocean currents-move heat easily. London's latitude (distance from equator) =51 degrees North(Moscow & Winnipeg-Canada)=much colder winters (-10 degrees or below)-warmer summers (20 degree) than London. UK climate influenced by North Atlantic Drift(warm ocean current)-->makes UK warmer than expected for its latitude.
DISTANCE FROM SEA:Sea heats up/cools down-slower than land-->places next to sea=milder in summer & warmer in winter.
ALTITUDE:Higher up place is-colder and wetter it is. For every 100m you go up-is 1/2 degree fall in temperature.
What makes the temperature extreme?
England and Australia have very different 'extreme' temp. England-30 degrees=EXTREME-->average weather for Australia-40 degrees=EXTREME. Both-extreme temp=above 10 degrees above average summer temp. UK-20 degrees & Australia-30 degrees.
HOTTEST PLACE ON EARTH: Lut desert-Iran-70.7 degrees-->place recorded covered by black lava=LOW ALBEDO. No-one lives there-too hot and dry-Nomads & Tourists pass through. Visitors must be careful-bring enough water-protect eyes from sun's rays
COLDEST PLACE ON EARTH:Antarctic-temp as low as -89.2 degrees-->sun's rays hit wide angle-not ver concentrated. 98% covered in ice=HIGH ALBEDO-reflects heat. No-one lives there permanently. Tourists & Scientists visit e.g. The British Antarctic Survey research station.
WIND:Movement of air from area of high pressure to low pressure-greater difference in pressure-stronger the wind.
How do we measure wind speed?
Anemometer measures wind by counting number of rotations per minute-Wind speed measure on Beaufort scale-ranges from 0(calm) to 12(hurricane). The windiest places on Earth
- Mt Washington-winds up to 372km/hr-->forms barrier to westerly trade winds
- In Antarctica ice sheets slope into sea-Katabatic winds cause downhill winds blowing 327km/hr
- Mt Everest reaches jet stream (winds in high atmosphere-very strong as little to slow down)-Wind speeds of 255km/hr-climbers choose May to climb-jet stream moves South them-wind=slower and safer
- Strongest winds recorded-408km/hr on Barrow Island(Australia) during Hurricane Olivia-1996
Tornadoes:Very strong rotating winds-smaller than hurricanes-winds reach up to 400km/hr--Tropical Storms=much larger-form over sea.
Winds in the UK
Highest wind speeds in UK-recorded on top of mountains-west of country. Strongest gusts=278kph-recorded top of Cairngorm mountains on 20 March 1986. Strong gusts recorded at low levels-along exposed coastal areas-Most recorded wind gusts occured in winter. Winter=windiest time of year in UK. This time of year-jet streams further south allowing more Atlantic storms to affect UK.
Localized effects with hills, mountains and coasts being winier than low-lying inland areas.Wind speed increases as you go upwards away from friction caused by Earth's surface.-explains windier coasts as sea surface produces less friction than land.
What is precipitation?
When warm air rises, is cooled down and condensation (change from water vapour to water droplets) occurs, forming clouds. Clouds bcome heavier-until release precipitation which falls as rain, hail, sleet or snow depending on temp of atmosphere.
Rain doesn't fall evenly around the world...
Along low pressure belt around equator rainfall is high. Where high pressure belt sits at 30 degrees N & S of equator-amount of rainfall=extremely LOW. Coasts of continents-much wetter. Mountainous regions experience high levels of rainfall.
Sun warms up ground during day-heats air above ground-warm air rises-as air rises it cools & condenses, forming clouds. This type of rain-common at equator in afternoon. Summer evening thunderstorms in UK-associated with convectional rainfall.
When band of warm air meets band of cold air-is called front. Warm air is less dense-rises up over cold(denser) air. As warm air rises it cools and condenses-rain that falls as result-called frontal rainfall. This type of rain-common in UK-polar front-cold air coming down from N pole meets warm air coming up from equator.
Air forced to rise over mountains-creates low pressure-air rises-cools & condenses forming clouds and rain-when air sinks down other side of mountain-creates high pressure-rainshadow effect. In UK mountains like the Pennines tends to be wetter on their western sides and drier on the east.
Most & Least Rainfall
Town of Cherrapunji in Khasi Hills, Northern India-record for most rainfall a month-9300mm in July 1861. Clouds blow in Bay of Bengal-pass over flat land of Bangladesh. When clouds meet Khasi Hills-forced to rise rapidly-relief rainfall. Wettest place in Britain-Seathwaite in Lake District receives average of 3552mm per year.
Atacama desert is driest hot desert in the world. Has average rainfall of 15mm. Lies in rainshadow of the Andes mountains.
The distinction of tropical storms: Hurricanes, cyclones & typhoons=names given to tropical storms-different parts of world. Form between 5 & 20 degrees N and S of equator-trade winds meet-water is warmer 26.5 degrees & deeper than 60m. Large body of warm water required-for evaporation & condensation to occur quickly enough so release of latent heat powers storm. Is why tropical storms occur in late summer & early autumn(oceans are warmest). Tropical storms DO NOT form at equator as here-coriolis effect(spin of earth) isn't strong enough.Storms measured on Saffir Sampson scale from 1-5 according to strength of winds.
The frequency of tropical storms: has been no increase trend in no.of tropical storms-Atlantic region seen increased no.since 1995. In future-tropical storms become more intense-stronger wind speeds & heavier precicpitation-as global warming means ocean waters will be warmer-faster evaporation=greater power.
Hazards associated with tropical storms:
- Strong winds
- Heavy rainfall-floods & landslides
- Storm surges-very low pressure-raises level of sea-huge waves-flooding, strucutral damage to buildings, large areas of land uninhabitable for long period, roads washed away/flooded, damage to ports.
Hazards of Tropical storms
Hurricane Katrina, USA Typhoon Haiyan, Philippines
Year:2005 Economic loss $:$250bn Year:2013 Economic loss $:£13bn
Category:5 Deaths:1500 Category:5 Deaths:6300
Winds km/hr:280km/hr Winds km/hr:315km/hr
Storm surge:8.5m Storm surge:6m
Diameter km:6.5km Diameter km:800km
Economic losses were far greater after Katrina as the USA is a AC. The number of deaths was far greater after Haiyan as the Philippines is a EDC.
CASE STUDY:Typhoon Haiyan, Philippines 2013
Causes: Typhoon Haiyan formed in Pacific Ocean-latitude of 7 degrees N of equator. Sea surface temp-over 26.5 degrees-deeper than 60m. Coriolis effect started storm spinning-storm moved westwards over ocean-gained speed from warm wateers. Government issued warnings-people had no where to go-Phillippine warning system has 4 levels-represented by 4 colours. People can find warnings on TV, radio or social media.
PRIMARY CONSEQUENCES are those that happen straight away
- most deadly hazard was storm surge-flooded coastal areas-InTacloban-5.2m high-destroyed 90% of city-including an evacuation shelter-many drowned
- Strong winds damaged buildongs
- 6300 died-over 1/2 a million left homeless
- People were killed by falling debris
- infrastructure(roads,electricity supply etc) were damaged
- Trees were uprooted & crops were damaged
- Barge was punctured & 85,000 litres of oil leaked into the sea
- $2,86 bn damage
SECOUNDARY CONSEQUENCES are those which occur in the days & weeks following disaster
- People forced to live in tents, without clean water or electricit
- Diseases spread rapidly through the tented settlements
- Roads were blocked by trees, making hard to travel
- 77% of farmers and 74% fishermen lost main source of income
Why were consequences so great?
Philippines is an EDC (emerging & developing country)-ranked 117th ou of 187 countries in the world for development. 25% of population live below poverty line of $1.25 a day. Area hit by typhoon was still recovering from Bohol earthquake a month before.
Typhoon Haiyan crossed densely populated areas. Large no.of people were affected by wind, rain and storm surge. Many of the people lived in poorly constructed houses that offered little protection from the storm.
EMERGENCY RESPONSES: Short-term aid was priority..FOOD, WATER, SHELTER etc.
- 50,000 solar lanterns were given out
- Australia sent medical staff, materials to build shelters, water containers & hygiene kits
- Social media hashtags were created to allow survivors to call for rescue or search for missing people
The emergency aid effort faced many difficulties, Airport was destroyed & was looting and crime.
LONG TERM RESPONSES: Once initial emergency had been tackled, in weeks & month following typhoon the focus turned towards long term aid
- By April, 107,000 households provided with tools, materials & technical advice to repair homes
- Seeds and fertilisers were given to help farmers get back on their feet
- Schemes were set up to pay people to clear away debris, repair infrastructure and replant mangroves(swamps) around coast to act as a natural buffer against future storms.
DROUGHT = less than average rainfall over specific time
A drought in UK is very different to drought in Ethiopia. UK=inconvenience--Ethiopia=matter of life or death-drought brings food shortages, starvation and death.
The distribution of drought-What causes drought? Drought is linked to long periods of HIGH air pressure-bringing DRY conditions.
EL NINO:In an El Nino year-water off coast of south america is warmer than usual-makes air warmer-air rises not sinking-low pressure instead of high-rain and floods. Reversed walker cell off the coast of Australia-air sinking instead of rising-high pressure-dry conditions-brings drought to Australia. El Nino as effects in terms of rainfall throughout the world. As well as Australia-droughts more common in Asia-in El Nino years.
LA NINA years=exaggerated version of normal year. High pressure off coast of South America higher than usual-drought in Peru and Chile. Off coast of Australia-low pressure even lower-flooding.
Consequences of Drought
The frequency of drought: Pattern of drought around world-changing over time-severity increased since 1940-->changing climate (warmer temp and less rain).
What are the CONSEQUENCES of drought?
- Shortages of food
- Shortages of water
- Bush fires
- Poor air quality
- Power cuts-for countries that rely heavily on HEP (hydro-electric power) to produce electricity
CASE STUDY:THE UK DROUGHT 2012
CAUSES of the drought:
- Unusual wind patterns brought dry, continental winds from east rather west (from Atlantic)
- Temp warmer than usual-more water evaporated from reservoirs and soils dried out
- Soil was baked hard by sun-impermeable(unable to soak in)
- Water used inefficiently-treated as never ending-wasted through leak old pipes
CONSEQUENCES of the drought:
- Farmers struggled-find water for crops & animals
- Dry areas-moorland-south wales, surrey, scottish borders-caught fire easily
- Tarmac melted due to heat
- More river water used than usual-problems with plants and animals
- Hosepipe van introduced to 20 million-stopped from watering gardens & washing cars
Responses to drought
RESPONSES to the drought: Water companies took action to keep water flowing.
- Permits granted so water could be extracted from rivers and underground aquifers
- Hosepipe bans issued to conserve remaining water
- Campaigns launched to ecourage people to use less water e.g. taking short showers instead of baths and turning off the tap whilst brushing teeth (saves 6 litres of water per minute)
How do plate tectonics shape our world?
Crust=surface of earth-rock layer forming upper part of lithosphere-cool and brittle-includes crust & top part of mantle. Lithosphere split into tectonic plates-plates moving slowly, 2.5cm/yr on top of lubricating called asthenosphere.
Two different types of crust:
CONTINENTAL CRUST forms land-made of granite-low density(light) & SEDIMENTARY/METAMORPHIC-on average 30-50km thick
OCEANIC CRUST found under oceans-much thinner, 6-8km thick-denser(heavier)-made of igneous rock basalt
Scientists know continents were all joined as super-continent=Pangea
How do they know this?
- Identical fossil and rock types-found in Western Africa and Eastern South America
- All fits like a jigsaw
Lithosphere split into 15 large TECTONIC PLATES & over 20 smaller-plates move very slowly on asthenosphere-where two plates meet =Plate Boundary
Heat from inside of Earth=GEOTHERMAL. Heat produced by radioactive decay in core and mantle-raises temp of core to over 5000 degrees. Convection currents in the mantle are created as the core heats particles at bottom-less dense and rise-further from core-cool and sink-continues.
There are DIFFERENT TYPES of Plate Boundary:
CONSTRUCTIVE BOUNDARY-Where the 2 plates are pulling apart
DESTRUCTIVE BOUNDARY-Where the 2 plates are moving towards each other
CONSERVATIVE BOUNDARY-Where the 2 plates are sliding past each other
3 types of Plate Boundary
CONSTRUCTIVE BOUNDARY: As 2 plates pull apart-convection currents bring magma to surface-easy for magma to escape so volcano forms-isn't very explosive. Lava that escapes=runny and flows far from crater before solidified-Volcanoes at constructive=shield volcanoes-wide base & shallow sides.E.g. Mid-Atlantic Ridge-Iceland-on ridge->line of volcanoes runs along ridge-including Eyjafallajokul(erupted 2010)
DESTRUCTIVE BOUNDARY: Oceanic & Continental plate move towards each other-oceanic plate(more dense) subducts under continental plate-melts-excess magma-pressure builds-forces way out as explosive volcano-lava=more viscous-at destructive-doesn't flow far before solidifying. Creates composite volcano-alternating layers of ash & magma. As oceanic plate subducts under continental-gets 'stuck'-pressure builds-plates move-results in earthquakes.E.g.Philippines plate subducted under Eurasian plate.
CONSERVATIVE BOUNDARY: 7moving in different directions & same direction-different speeds. 2 plates moving past-get stuck-pressure builds-finally move past-pressure released results in earthquakes.E.g.San Andreas fault in USA-North American plate moving 2-3cm/yr-pacific plate moving 7-11cm/yr--get 100-50 small tremors/yr & occasional big earthquake.e.g.1906 San Francisco. San Andreas fault-2004-moved 50cm-magnitude 5 EQ-small damage-preparing for next 'big one'.
Boundary & Earthquake
COLLISION BOUNDARY: 2 continental plates collide-same density-push upwards-creating fold mountains like Himalayas-strong EQ can form as plates move-can trigger earthquakes close to surface.
The distribution of earthquake: Majority earthquakes occur at plate boundaries-with large no.along western edge of Pacific Plate
How do earthquakes form? Two plates slide past each other-get 'stuck'-pressure builds-finally move past-pressure released as earthquakes
The FOCUS is point underground where EQ starts-deep focus earthquakes form more than 70km below surface
The EPICENTRE =directly above focus on surface-where shaking will be strongest
HOTSPOT VOLCANOES:in middle of plate-where hot plume magma rising to surface & weak point in crust-magma breaks through-creates volcano.example=Hawaii-plate continues to move (continental drift) over hotspot-results in new volcanic islands forming over time. Hawaii=chain of volcanoes
CASE STUDY:NEPAL EARTHQUAKE 2015
CAUSES: At collision fault-where Indian & Eurasian plate collide-push up-(forming himalayas)-Indian & Eurasian plate push together-2cm/yr-build enormous pressure-plates moved 2015-century worth pressure released.
- Powerful magnitude 7.8 earthquake-near Nepal capital-Katmandu-25 April-no warning-no escape
- Focus 15km deep-cause-enormous shaking-surface
- Crust moved 3cm-some places
- Epicentre of quake-50miles northwest Katmandu-followed by large 6.6 magnitude aftershock-tremors felt as far as New Delhi & Dhaka-Bangladesh
- 8635 dead
- 19 climbers killed- EQ=avalanche triggered Mt Everest
- People traumatised-->by EQ
- More 1/4 Nepal population affected
- thousands forced-live in tents
- 1.4mill in need of food
- $5bn to rebuild=20% Nepal GDP-no money left for=hospital, schools, roads,etc
- Fewer tourists=tourist attractions ruined=less money
- Farmer field in debris-crops fail
- Debris in river-poor water quality
- mountainous lands-Nepal-more danger-->steep slopes unstable-547 landslides,e.g.Kali Gandaki landslide-after EQ-buried 25 houses
- India sent aircrafts-10 tonnes of blankets inside-50 tonnes water-22 tonnes food-2 tonnes medical supplies-mobile hospital-40 disaster response team-rescueers with dogs
- USA, UK and China-disaster response teams
- Person rescued-120 hrs after EQ
- Criticised aid effort-not enough-people left in tents-aid effort delay because infrastructure-airport shut-roads in poor condition
How does technology have the potential to save liv
Methods used to mitigate EQ damage------->Mitigation=act of reducing severity of something
PREDICTION: No way to predict EQ -data moving plates collected by satellites & seisometers= GIS hazard map=warnings. Way to predict-->look for seismic gaps-along fault-haven't experienced EQ activity-most likely pressure building
EARLY WARNING SYSTEMS: Once seismic waves start-warnings sent out. In 2011-Tokyo-got 30sec warning on mobile-smartphones developed-measure ground shaking-warn EQ about to happen
BEING PREPARED: People encouraged to have survival kit in homes-kit includes=first aid, high energy food, torch, wind up radio, blanket, whistle, face mask, water purification tablets. Areas prone to EQ-regular EQ drills-practice if happens-in school-->DROP, COVER & HOLD ON
BUILDING DESIGN: EQ proof buildings cross bracing-forms triangles-some buildings=large base & tapered shape-decrease as taller
EQ proof building-LIDC's=lack money & resources-can't construct EQ proof building-simple building made safer