Hazardous Earth Flashcards
why are low lying coastlines vulnerable to tropical cyclones
they are vulnerable to storm surge flooding caused by low air pressure within cyclones
vulnerable to large waves causing flooding driven onshore by intense winds
what are 2 data presentation techniques that would show contrasting impacts of a hazard event on different countries
bar graph and choropleth map
what is the best technique to measure volcano type
cross section
what are 2 ways to predict volcanic eruptions
1) using thermal imaging techniques and satellite cameras to track temperature fluctuations around the volcano which increase when an eruption is imminent
2) measuring gases released by the volcano in order to know the chemical make up of the gases which have increased sulphur content when an eruption is imminent
what are 2 ways to predict an earthquake
1) laser beams can be used to detect minor plate movement just before an earthquake
2) a seisometer is used to pick up vibrations in the earth’s crust. An increase in vibrations could indicate an earthquake is about to happen
what is atmospheric circulation
movement of air in the atmosphere dominated by 3 large circulation cells in each hemisphere (hadley, ferrel, polar)
what is the cause and air pressure of convection air movement
cause; when high amounts of solar radiation heat the ground which heats the air above causing the air to rise. As it rises it cools and condenses forming water droplets and clouds
Air pressure; low as air is moving upwards away from the surface
what is the cause and air pressure of subsidence air movement
cause; in places with low intensity solar radiation like the poles the cold dense air sinks towards the ground. As it sinks it warms up so can hold more moisture which prevents clouds forming
air pressure; high as air is sinking
how does volcanic activity cause climate change
large eruptions emit dust and sulphur dioxide into the atmosphere which block out or absorb solar radiation so the earth cools
how do sunspots cause climate change
sunspots are darker areas on the sun’s surface showing greater solar output. They come and go in cycles of about 11 years
how do orbital changes affect climate change
shape of the earths orbit becomes more or less circular over a period of 100,000 years
the tilt of the axis varies between 21 degrees and 24 over 40,000 years
this changes the amount of solar energy received at the earths surface
how can asteroid collisions affect climate change
similar to volcanic eruptions in which dust and ash is thrown into the atmosphere blocking incoming sunlight
how do ice cores act as evidence for climate change
they are tubes of ice containing trapped air bubbles dating from when the ice was formed showing how muc CO2 was in the atmosphere at that time
how do tree rings act as evidence for climate change
wide ring means it was warm but a narrow ring indicates harsh conditions like cold or drought
what is thermal expansion
an increase in the volume of water as a result of increasing temperature
what are human reasons for uncertainty
future population growth is unknown
emissions per person are linked to wealth but future average wealth is uncertain
humans may carry on polluting or may make a strong effort to reduce emissions
new technology could replace fossil fuels
what are physical processes leading to uncertainty
oceans may absorb a lot of co2 but their ability to do this could stop
warmer world could be cloudier, clouds could reflect more solar radiation back into space reducing the warming
ice may start to melt much more quickly
where are tropical cyclones known as hurricanes
North Atlantic ocean and East Pacific
where are tropical cyclone known as typhoons
Indian ocean
what is the coriolis force
a rotational force that affects liquids and gases, caused by the earth’s rotation
where are source areas for tropical cyclones found
5-15 degrees north and south of the equator as this is where the ocean is the warmest
why are tropical cyclones not found between 0-5 degrees north and south of the equator
because the coriolis force that creates their rotation is too weak
how are tropical cyclones formed
when ocean temperatures are 26.5 or above
warm air above the ocean rises leading to strong convection and the formation of thick clouds
as more water is evaporated from the ocean it rises and condenses forming clouds releasing latent heat into the storm (energy source)
storm clouds combine into one large storm which begins to rotate
what physical hazards can happen when a cyclone makes landfall
intense wind intense rain landslides powerful waves storm surge
what is the litosphere
rigid outer layer of the earth made of the mantle and the crust
what are the 2 crusts that make up the earth’s tectonic plates
continental crust and oceanic crust
what is the continental crust
low density
makes up most of the land area of the earth
25-80km thick
dominated by rocks that cooled below the surface eg granite
what is the oceanic crust
high density
6-8km thick
made up of rocks eg basalt
what is the asthenosphere
partly molten layer beneath the litosphere on which the litosphere slides
what are convection currents
circular movements of heat within the Earth’s core and mantle which drive plate tectonic motion
what 3 things cause plate motion
plates are pushed along by convection currents moving sideways just below the crust
elevated parts of divergent boundaries create a force called gravitational sliding
slab pull- old, dense oceanic plate sinks at convergent margins pulling the plate down the mantle
what are conservative plate boundaries
where 2 plates slide past each other
what are convergent (destructive) plate boundaries
where 2 plates collide
what are divergent (constructive) plate boundaries
where 2 plates move apart from each other
what is subduction
the process whereby a dense oceanic plate sinks back into the upper mantle
what are fold mountains
chains of high mountains produced when tectonic plates collide and the continental crust crumples and is forced upwards
what is the fault
major cracks in the crust. when there is movement on the fault often an earthquake will start
what are hotspots
places where there is a rising plume of heat from the mantle in the form of an isolated column. The heat generates magma in the upper mantle which erupts as basaltic volcanoes
creates a chain of volcanic islands
how does a volcano erupt
when magma beneath the earth’s crust pushes up through fissures and vents and erupts at the surface as lava, ash and gas
what is the difference between composite volcanoes and shield volcanoes
composite are more dangerous and found on convergent plate boundaries.
Shield volcanoes are found on divergent boundaries or hotspots
what is a tsunami and how are they caused
series of very destructive ocean waves. sub sea earthquakes can displace the seabed and this causes a tsunami
