Topic 1- Hazardous Earth Flashcards
What are ocean currents
Ocean currents are large scale water movements that transfer heat energy from hotter regions to cooler regions
What are surface currents
Surface currents are currents caused by winds that carry heat energy away from the equator e.g the gulf stream carries heat energy from the carribean to western europe
What are deep ocean currents and how are they created
Deep ocean currents are ocean currents caused by differences in water density.
- When water at the poles freezes, the surrounding water gets saltier-increasing its density.
- This more dense water sinks below warmer water following at the surface -creatinh an ocean current
- Eventually this water also cools and freezes , moving water round in a bit circulation called the thermohaline circulation
How does global atmospheric circulation create arid conditions
Sinking air from ferrel and hadley cells meeting causes high air pressure and prevents rainfall. There is little to no rainfall all year round and temperatures are hot or warm
How does global atmospheric circulation create high pressure at the poles
Sinking air from the polar cells creates high pressure at the poles. Temperatures are low all year and there is little to no rainfall
How are tropical areas caused by global atmospheric circulation
Rising air from two hadley cells meeting causes low pressure and lots of rainfalls. Temperatures are high and rainfall is high
How can tree rings give evidence on natural climate change
Tree rings can give evidence on natural climate change as tress produce one ring each year. The thickness of the ring depends pn the climate that year . When its warmer the climate the thicker the tree rings are. Scientists can tell what the climate was like in different years by looking at the thickness of the tree ring and dating it back to a year
How can ice sheets give evidence of natural climate
Ice sheets are made up of layers of ice. With one sheet being produced each year. Scientists can drill into sheets to get ice cores. By analysing the gases trapped in the ice cores from different years scientists can track the temperature from different years e.g the vostock ice core shows temperatures from 400,000 years
How can historical records give evidence of natural climate change
Historical records can stretch knowledge of the climate back further. They can indicate at the temperature and climate by listing the days of rain or the dates of harvest ( early harvest= warmer weather)
-Paintings if frozen rivers show europe was regurly much colder 500 years ago than it is now
What is the quaternary period
The quaternary period is an geological period that has lasted from 2.6 million years ago to now
How has the climate changed since before the quaternary period to now
The climate before the quaternary period was warmer and stable
whereas the climate during the quaternary period has switched between glacial cold periods that last 100,000 years and interglacial , warmer periods that last 10,000 years
For the last 15,000 years it has been a warmer interglacial period
How has eccentricity (suns orbit) caused natural climate change
The path of the suns orbit round the earth changes from a perfect circle to an ellipse (oval) every 100,000 years
When the suns orbit is more circular it causes the climate to be significantly warmer than when it is an ellipse.
This leads to interglacial and glacial periods depending on the suns orbit (glacial if ellipse , interglacial if ellipse) and causes the climate to change naturally
How does the tilt of the earth cause natural climate change
The earth axis is tilted at an angle as it orbits the sun. This angle changes over the period of 22,000 years
When the earth tilts away from the sun the seasons are less pronounced and the climate is colder. When the earth tilts towards the sun the seasons are warmer and the climate is warmer
How does precession(wobble) cause natural climate change
- The earth wobbles on its axis on a cycle of 22,000 years
- When the earth wobbles towards the sun the earth gets hotter
- When the earth wobbles away from the sun the earth cools down
How can major volcanic eruptions affect the climate
Major volcanic eruptions eject large amounts of material e.g ash into the atmosphere
This material reflects the suns rays which causes the earths surface to cool
Volcanic eruptions cause short term changes to the climate e.g mount tambora in Indonesia in 1815
How can solar output cause natural climate change
The suns output of energy isnt constant , it changes on short cycles of 11 years and longer cycles of several hundred years
In periods where the solar output is reduces the surface of the earth is cooler and in periods where solar output is increased the surface of the earth is warmer
How do asteriod collisions cause climate change
Asteroid collisions with the earths surface throw up large amounts of dust into the earths atmosphere . This prevents the suns rays from reaching the earths surface, leading to a period of coolinh.
How ahve historical records shown evidenve of the medival worm period between 900-1200
Harvest records show that england was warm enough to grow large amounts of grapes
Tree rings also show this was the case with england believed to be 1° warmer than yoday
How do historical records show evidence of a little ice age
The little ice a age was a period of cooling following the medival warm period
Paintings from the 17th century show the London frost fairs which took place on a frozen river thames
Historical records say that arctic ice reached as far as Scotland
What are the stages in the greenhouse effect
1) the temperature of the earth is controlled by the ingoing heat it gets from the sun and the heat it loses to space
2) The incoming energy from the sun is short wavelength radiation whereas the energy coming from the earth is long wavelength radiation
3) gases in the atmoshpere act like insulators- They allow short wavelength radiation in but trap long wavelength radiation in order to maintain the earths temperature
4) This is called the greenhouse gases
What are greenhouse gases
Greenhouse gases are gases that trap heat energy in the atmosphere
They are alll different strengths e.g methane is stronger than co2
What happens when there is too much greenhouse gas in the atmosphere
Where there is too much greenhouse gas in the atmosphere too much heat is trapped and the earth warms uo
How has farming contributed to the increase in greenhouse gas emmitions
- farming livestock emits alot of methane
- Rice paddies contribute to global warming as flooded fields emmit methane
- Trees absorb and store co2.When land is cleared of trees for agriculture the absobtion stops and the co2 is released back into the atmsphere. Contributing to global warming
How has industry increased the greenhouse gas concentration
- Most industrial processes use alot of energy e.g melting parts and also release greenhouse gases e.g making cement releases co2
- Industrial waste may end up in landfill sites where it decays , releasing methane
How has transport led to an increase in greenhouse gases
- Cars planes,lorries and ships run on fossil feuls which release greenhouse gases when burnt
- Car ownershup is going up in developing countries. This means there are more cars on the roads which leads to more congestion so cars have their engines on for longer when waiting in traffic
How does declining artic ice show human activity is causing climate change
- Sea ice forms around the poles when ocean temperatures in winter drop below -1.8°. This ice then melts in the summer when its warmer
- The extend of sea ice in winter has decreased by more than 3% every decade for the past 35 years. This shows the earth is getting warmer and climate change is occuring
How does glocal temperature rise show human activity is causing climate change
- Since 1880 the temperature of the earth has risen by nearly 1°
- The temperature of the earth is predicted to rise from between 0.3-4.8° from 2005 to 2100
- The 10 warmest years on record have all been since the year 2000 showing human activity is causing climate
How do extreme weather events show that humans are partlyresponsible for climate change
- Since 1950 there has been a higher frequency of heat waves and less cold weather extremes
- Between the years 2010-2014 more rainfall records were broken than in any other decade (even though only 4 years )
- 2013 was one of the wettest years ever recorded and December 2015 was the wettest month on UK record
What are the two reasons behind sea level rise
The two resons behind sea level rise are eustatic sea level rise and thermal expansion.
- Due to temperatures increasing glaciers are shrinking and ice sheets are melting . The melting of ice sheets means that water previously stored as ice on land is being returned to the oceans causing sea levels to rise
- as water gets warmer it expands. This means that with climate change oceans are expanding as it gets hotter and sea levels are rising
- Since 1901 sea levels have risen by 0.2m
What are the main consequences of climate change on people (6)
- Due to climate change some areas are becoming ao hot and dry taht tehy are becoming impossible to inhabit
- Deaths due to the increased heat have gone up
- Low lying coastal areas have been lost to sea or flood so often they become uninhabitable. This has great affects and means there is mass migration to another place which then subsequently becomes overcrowed
- Climate change has led to lower crop yeilds og certian plants e.g maize. This lower crop yield has meant that there is more malnutrition and more deaths from starvation in some areas
- Climate change also has led to an increase in extreme weather events which means more money needs to be spent predicting these events, reducing the impacts of them, and rebuilding after them
What is the IPCC and what does it do
The IPCC are the intercontinetal panel on climate change. The panel is made up of scientist who use models to predict how the climate could change and what the consequences of these changes could be (using data on greenhouse gas emmitions and physical processes)
-They have four representitive concentration pathways which outline the possible outcomes of the climate cahnging
What are the four scenarios which the IPCC have outlined
The 4 scenarios of the IPCC are
Scenario 1-Greenhouse gas emitions peak but then reduce significantly
Scenario 2& 3-Greenhouse gas emmitions increase but then become stable and level off
Scenario 4- This is where greenhouse gas emmitions continue to increase until they are really high
Why is it difficult to predict how much the climate will change and what the impact will be of it
- It is difficult to predict how the climate change because:
- It is difficult to know how emmisions will change as emmisions will change as global population and economic development change. These two things are very hard to predict
- Climate change is also due to many natural processes that we do not understand. This means that it is difficult to predict the climate as we do not know how these natural processes will change
- There is no knowledge on wether there will be any attemps to reduce greenhouse gas emmisions and how succesful they will be
What are the conditions for tropical cyclones
- For tropical cyclones to occur the sea temperature must be 26.5° or above and windshear(difference in wind speed) between the lower and upper parts of the atmosphere must be low
- The source area of most tropical cyclones is between 5° to 30° north or south of the equator
At what time of year do most tropical cyclones occur ?
Most tropical cyclones occur from November to April in the southern hemisphere and June to November in the Northern hemisphere
How are tropical cyclones formed and what is their path like
- Warm mosit air rises , cools and condenses. This releases a huge amount of energy that causes the storm to be powerful . The rising air creates an area of low pressure in which surface winds increase
2) the earths rotation deflects the path of the surface winds , causing them to spin
3) The cyclones move west because of easterly winds near the equator
4) when cyclones travel further from the equator they curve east due to the mid latitude westerliers
At what points do cyclones intensify and dissapate
Cyclones intensify when they move over warm water as warm water supplies the energy for the cyclones
Cyclones dissapate over land and cooler water as they are further away from the energy source of the warm water . They also dissapate when there is a change in windspeed
How will climate change affect tropical cyclones
Climate change will cause more places to have sea temperatures pver 26.5 degrees which means there will be more tropical cyclones
What are the structural features of a cyclone
Cyclones are usually circular, hundreds of km wide and usually last 7-14 days
- The centre of the cyclone is called the eye . It is up to 50km wide . It is caused by descending air. The eye has low pressure, light winds , no clouds,no rain and a high temperature
- The eye is surrounded by the eyewall where theres spiralling rising air and strong winds, storm clouds, low termperature and torrential rain
- Towards the edges of the cyclone wind speed falls, the clouds become smaller and more scattered. The rain becomes less intense and the temperature increases
What are the physical hazards caused by tropical cyclones
The physical hazards caused by tropical storms include:
- high winds-windspeeds in tropical cyclones can reach 250km/h
- Intense rainfall-tropical cyclones can drop trillions of litres of water as rain on an area. The rain gets heavier the closer you go to the eye of the storm
- Storm surges - This is where sea levels rise as a result of low pressure and high winds
- flooding- storm surges and high winds pushing waves towards the shore cause coastal flooding
- Landslides-heavy rainfall makes hills unstable , causing landslides
What impacts do tropical cyclones have on people (5)
Tropical cyclones may have thse impacts on people :
- Tropical cyclones may cause people to drown because of the strong currents creted by storm surges and floodwater
- High windspeeds and floodwater can damage buisnesses and homes and leave people homeless
- Electricty can be cut out as electricity cables can be knocked down by strong winds or flooding
- Flooding causes sewage overflow which can contaminate water supplies
What are other human impacts of tropical cyclones
- The shortage of clean water and lack of sanatation means that diseases spread very quickly after the cyclones
- The cyclones destroy crops and kill livestock which can lead to food shortages in poorer countries
- Unemployment rates rapidly go up after cyclones as buisnesses are damagaed and destroyed
- Damaged roads can make it hard for aid and emergecy services to reach the worst effected areas
What are the impacts on the environment of tropical cyclones
- Trees can be uprooted by high winds which can damage and completely destroy woodland areas
- Storm surges can damage coastal habitats and erode beaches
- Flooding caused by storm surges can pollute freshwater environments with saltwater
- Landslides can deposit material into lakes and rivers which can kill fish and animals
- Flooding can damage industrial factories on the coast,This can cause harmful chemicals to leak into the environment , polluting it
How can a country or area be physically vunerable to tropical cyclones
- Low lying coastlines can be more vunerable to flooding caused by storm surges and large waves caused by high winds
- Areas in the path of tropical cyclones are more likely to be hit more frequently
- Areas with steep hillsides are more likely to experience landslides
How are some areas more vunerable to the affects of tropical cyclones
Some poorer areas are more vunerable to the affects of tropical cyclones because
- Many people depend on agriculture for livelyhood, this is often lost
- People do not have insurace to cover the cost of repairing things damaged by the cyclone
- buildings may be of poorer quality so are more easily destroyed
- Health care isnt as good so not all patients may be treated
- There is less money to spend on flood defences and training emergency teams
- People may be harder to rescue because of poorer infrastructure
-However , rich countries are also affected as lots of expensive infrastructure may be damaged
How can predicting tropical cyclones help people prepare and respond to them
When and where tropical cyclones hit can be predicted. Scientists can use sattelites and weathering monitering to predict when and where a cyclone will happen .
- Scientists can also use monitoring systems to predict the path of the cyclone
- They can use the windspeed of the cyclone to predict the magnitude of the cyclone
- Predicting when and where the cyclone will hit can give people more time to evacuate and protect their homes and buisnesses
How can other stratergies be used to help people prepare and respond to tropical cyclones
- Warning stratergies can be used to alert people to tropical cyclones so they have enough time to leave their homes and get to safety . This reduces the amount of deaths and injuries.
- Evacuation plans can be set out by the governemnt to direct people on where to go in an emergency . This can again reduce casualties
- Emergecy services can be trained to deal with disasters to help reduce the number of people killed
How can defences be used to defend areas from the affects of tropical cyclones
Defences can be built along areas to protect them from storm surges and buildings can be designed to be protected from flooding and storm surges e.g by being put on stilts
This reduces the amount of buildings destroyed,people killed, people made unemployed and people made homeless
What is the profile of a tropical storm that has hit a developed country
Name :Hurricane Katrina
Magnitudeof hurricane Katrina :category 3 at landfall
Place : South East USA
Date of Hurricane Katrina : 29th August 2005
What is the profile of a tropical cyclone in a developing country
Name:Cyclone nargis
Magnitude of cyclone Nargis : category 4 at landfall
Place : Irrawaddy delta in Myanmar
Date of cyclone nargis : 2nd May ,2008
What was the forecasting of hurricane katrina like in a developed country
- The USA has a sophisticated monitoring system that can predict if a where a cyclone will hit
- The national hurricane centre in Florida can track and predict hurricanes using sattelite images and planes that collect weather data on approaching storms
What was the forecasting of cyclone nargis like in a developing country
- Myanmar doesnt have a dedicated monitoring centre for tropical cyclones
- Myanmar dowsnt have a radar network that can predict the height of storm surges or waves caused by tropical cyclones
What was the evacuation and warning like for hurricane katrina
The NHC issued a hurricane warning for the states of Alabama , Mississippi and Louisiana on the 26th August. It continued to track the hurricane, updating the government on where it would hit
-Louisiana and Mississipi were declared states of emergency . 70-80 % of New Orleans residents were evacuated before the hurricane reached land , this reduced the numbers of people killed as lots of the places were the hurrican hit had already been evacuated
What was warning and evacuation like in Myanmar
- Indian weather agencies warned the government of Myanmar that Cyclone Nargis would hit 48 hours before it did
- Warnings were issued on TV and Radio but did not reach people in poor rural communities . This meant more people were killed as they did no know what to do or where to evacuate to
- There were no emergency preparation plans, no evacuation plans and no early warning systems in place
What were the defences like against hurricane katrina in the USA
- The defences against the hurricane failed.New Orleans was very badly damaged as the flood defences that were meant to protect the city failed.
- This led to widespread flooding with 80% of new orleans underwater
What were the defences against cyclone Nargis like in Myanmar
Mangrove forests that provide natural protection for the cost had been heavily chopped down in the decade prior to Nargis hitting, this reduced the natural protection from the cyclone
What impacts did hurricane Katrina have on the environment
- Hurricane Katrina damaged some coastal habitats such as sea turtle breeding beaches
- Hurricane Katrina destroyed wildlife conservation areas such as Breton national wildlife park in Louisana
- Flooding caused by Hurricane Katrina damaged Oil refineries in Louisana which led to massive oil spills that further damaged the environment
What impact did cyclone Nargis have on the environment
- 38000 hectares of mangrove forests were destroyed
- 14000 km2 of land in the irrawaddy delta was flooded as it was only just above sea level
- The floooding caused erosion and increased salt content of the land
What impacts did hurricane katrina have on people
- Hurricane Katrina killed more than 18000 people
- Hurricane Katrina destroyed 300,000 homes and left hundreds of thousand of people homeless
- Hurricane Katrina left 3 million people without electricity
- 230,000 jobs were lost due to damaged buisnesses due to hurricane katrina
What were the impacts on people of Cyclone Nargis
- Cyclone nargis killed around 140,000 people
- Cyclone Nargis destroyed 450,000 homes and damaged 350,000
- Cyclone Nargis destroyed 65% of the rice paddies in the Irrawaddy delta which left many people without livelyhoods
- Cyclone Nargis meant that alot of people suffered from disease due to contaminated water and poor sanitary conditions
How do covection currents work and how do they cause tectonic plates to move
1) Tectonic plates float on mantle
2) the radioactive decay of some elements in the core and mantle generates a lot of heat
3) This heat heats up the lower parts of the asthenosphere
4) This heating up of the lower part of the asthensphere causes it to become less dense and rise
5) When this lower part of the asthenosphere rises towards the upper part of the asthenoshpere it cools, becomes more dense and sinks
6) These movements of semi - molten rock in the asthensophere are called convection currents
7) These covection currents cause drag at the base of tectonic plates which causes them to move
What happens at a convergent plate boundary
At a convergent plate boundary two plates are moving towards eachother
When a continental plate is moving towards an oceanic plate, the more dense oceanic plate is forced down into the mantle where it is destroyed. This forms ocean trenches and volcanoes
When a continental plate moves towards a continental plate the ground folds and is forced upwards creating mountain ranges
What happens at a divergent plate boundary
At a divergent plate boundary two plates move away from each other creating a gap . Magma rises from the mantle to fill the gap creating new crust.
What are conservative plate boundaries
Conservative plate boundaries are where two plates are moving in the same direction but at different speeds. This causes friction and earthquakes can occur
How do volcanoes form at convergent plate boundaries
At convergent plate boundaries the oceanic plate goes under the continental plate because it is more dense
The oceanic plate moves down into the mantle where it is melted and destroyed
A pool of magma forms
The magma rises through cracks in the earths crust called vents
The magma erupts on the surface , creating volcanoes
How do volcanoes form at divergent plate boundaries
At divergent plate boundaries ,magma rises through the gap created by the two plates moving apart
Forming volcanoes
How do hotspot volcanoes form
Hotspots occur at hotspots under tectonic plates
Hotspot volcanoes form when a plume of hot magma moves from the mantle towards the surface, causing an unusually large flow of heat from the surface to the crust
Sometimes the magma can break through the crust an reach the surface, causing an eruption to happen and a volcano to form
Hotspots remain stationary over time but the crust above them can move , creating large chains of volcanic islands
Describe composite volcanoes
- Composite volcanoes occur at convergent plate boundaries
- The subducted oceanic crust contains a lot of water. This water reacts with magma and forms gases, which cause the oceanic crust to erupt
- The eruptions are very explosive and start with erupting ash , this deposits a layer of ash around the volcano
- The volcanoes erupt andesitic lava which has a high scilica content so is thick and sticky . The lava doesnt flow very far so formsa steep sided cone around the volcano
Describe shield volcanoes
- Shield volcanoes occur at divergent plate boundaries and hotspots
- They are not very explosive and only erupt lava
- They erupt basaltic lava which is very runny and spreads over a wide area , forming low gentle sides of the volcano
How do earthquakes form at covergent plate boundaries
- Tension builds up when the two plates get stuck as one is moving below the other towards the mantle at convergent plate boundaries
- The plates eventually jerk past each other sending out shock waves ( which is the earthquake)
How do earthquakes form at divergent plate boundaries
Tension builds between cracks in the plates as they move away from each other at divergent plate boundaries
They eventually jerk past each other , sending out shock waves ( the earthquake)
How do earthquakes form at conservative plate boundaries
Tension builds up when plates that are grinding past each other get stuck at conservative plate boundaries
They eventually jerk past each other , sending out shockwaves ( which is the earthquake)
What is the focus of an earthquake
The focus of an earthquake is the point in the earth where the earthquake starts
What creates a shallow focus earthquake
A shallow focus earthquake is created by tectonic plates moving near or at the earths surface.
The focus of a shallow focus earthquake can be between 0km - 70km below the earths surface
What are deep focus earthquakes caused by
Deep focus earthquakes are caused by crust that has previously been subducted into the mantle moving towards the centre of the earth and then heating up or decomposing
Deep focus earthquakes can have focuses between 70km-700km below the earths surface
Which type of earthquakes do more damage at the surface , deeper focus earthquakes or shallower focus earthquakes ?
Deeper focus earthquakes do less damage that shallow focus earthquakes. This is because shock waves from deeper focus earthquakes have to travel through more rock to reach the surface. This reduces their power when they reach the surface
What are tsunamis and what are they caused by
- Tsunamis are a series of enormous waves caused when large amounts of water get displaced
- Underwater earthquakes move the seabed and displace lots of water sending out waves from the epidcentre
- The focus of the earthquake determines the size of the tsunami . If the earthquake has a shallower focus more water will be displaced as the focus is closer to the earths surface and the tsunami will be larger
Describe the profile of a recent earthquake that has hit Japan
- On the 11th March 2011 a powerful earthquake struck north east Japan
- It measured a 9 on the richter scale and triggered a tsunami that overwhelmed coastal and inland areas
- Japanese scientists had predicted an earthquake but the earthquakes magnitude was larger than expected
Describe the profile of a recent earthquake in Haiti
- On the 12th January 2010 a major earthquake struck the west of Haiti
- It measured a 7 on the richter scale . It had a very shallow focus and was only 25km south of the capital. This caused major devestation in the city
- It was completely unexpected
What were the primary impacts of the earthquake in Japan
- The earthquake caused thousands of buildings to be damaged in Japan
- The earthquake caused severe liquification ( where waterlogged soil behaves like a liquid) which caused buildings to tilt and sink into the ground
What were the primary impacts of the earthquake in Haiti
- The earthquake in Haiti killed 316,000 people and injured 30,000 more
- Many houses in Haiti were built so poorly that they instantly collapsed. 180,000 houses collapsed and 1.5 million people were made homeless
- All 8 hospitals in port au prince were damaged and badly destroyed.
- Around 5000 schools were damaged and collapsed
- All major communication links in ports and major roads were damaged beyond repair
What were the secondary impacts of the earthquake in Japan
- In Japan, The earthquake triggered a tsunami which killed thousands of people
- The earthquake also damaged and qdestroyed hundreds of thousands of buildings in Japan. This left over 230,000 people homeless
- The tsunami cut off power supplies to the Fukashima nuclear power plant, this caused a meltdown
- Road and rail connections were severley destroyed by the earthquake and the tsunami with 325km of railway being washed away
What were the secondary impacts of the earthquake in haiti
- Cholera spread through the squatter camps and killed 8000 people
- With clothing factories destroyed ( made up 60% of exports) and tourism stopped , economic losses increased in Haiti. 1 in 5 jobs were lost
- Looting and crime increased as the government and police force collapsed
- The port area was destroyed which meant aid couldnt be delivered
What was the short term relief like after the earthquake in Japan
- International aid and search and rescue teams were brought in very quickly after the earthquake in Japan
- Rescue workers and soldiers were sent in to help deal with the aftermath
- Power suppplies,communications and transport links were restored in the weeks after the earthquake
What was the short term relief like in Haiti
- With government buildings destroyed, emergency aid was initially slow
- International aid and search and rescue teams were sent in to help trapped people
- food,water,medical supplies and temporary shelter was provided by the USA
- The Uk disaster commision raised over £100 million for Haiti
What was the effect of long term planning in Japan
- In Japan , the authorities gave an advanced warning of the eathquake and the tsunami which gave people time to evacuate and get to higher ground
- Despite strong shaking in Tokyo, no buildings collapsed because of the building design to prevent earthquake damage
- No one died on bullet train because of an automatic braking system
What was the effect of long term planning in Haiti
- The goverment in Haiti were completely unprepared for an earthquake. There were no monitoring systems in place in the case of an earthquake and no advanced warning systems .
- The government still managed to move 235,000 people to less damaged cities
