Flashcards in Hazardous Earth Deck (141):
Why is it hot at the equator and cold at the poles?
The sun rays are strongest at the equator which means they are more concentrated on a small surface area therefore leading to hotter temperatures whereas at the Poles the suns rays are spread out over a larger surface area meaning it is colder
Why do we get rain at the equator but it is dry at the Poles?
The equator is situated between the Hadley cells which is an area of low pressure where warm, moist air rises 15km in the air and travels north and south 30 degrees of latitude and cannot hold as much water therefore precipitation occurs, however the Poles are situated between the Polar cells which is an area of high pressure where cool, dry air sinks
The inter tropical convergence zone which is a belt of low pressure circling the earth generally near the equator where trade winds of the Northern and Southern Hemisphere come together
Define atmospheric circulation
The large scale movement of the air by which heat is distributed on the surface of the earth
Why is the North Atlantic drift important?
It’s relatively warm waters are responsible for moderating the climate of Western Europe so that winters are less cold than would be expected at its latitude
Explain ocean circulation
Cold dense water at the poles sinks pulling warmer water from lower latitudes in which is then cooled by polar temperatures. The cycle continues
Define climate change
A change in global or regional climate patterns which is long term
What is the difference between weather and climate?
Weather is what the conditions of the atmosphere are over a short amount of time whereas climate is how the atmosphere behaves over a long period of time
How do volcanic eruptions cause climate change?
Volcanic eruptions produce sulphur dioxide and ash which, if they rise high enough, will be spread around the earth in the stratosphere by high level winds. This blanket of ash and sulphur dioxide blocks sunlight from reaching the earths surface therefore cooling the planet
How do asteroid collisions cause climate change?
Asteroids hit the earth once every 500,000 years, dust flies up and blocks the sunlight therefore cooling the planet
How do sunspots cause climate change?
Lots of sunspots mean more solar radiation is being given out to the earth which heats the planet
How do Milankovitch cycles cause climate change?
Sometimes the earth’s orbit is a circle but every 100,000 years it becomes more of an ellipse, an ellipse makes the earth hotter. Sometimes the earth is tilted more towards the sun (making it hotter) and other times less. The direction of the earths axis changes because it spins like a spinning top which changes the amount of solar irradiation each hemisphere receives during each given season.
How do ice cores allow us to identify climate?
Ice cores are big cylinders of ice which have been drilled through glaciers up to 3km deep and 500,000 years old. Within the core are air bubbles which contain carbon dioxide. Scientists observe the amount of carbon dioxide in the air bubbles to determine how much carbon dioxide was in the air at the time. The more there was, the hotter it was.
How do tree rings allow us to identify climate?
When conditions are good for growing (warm and wet) the tree ring grown is wide but is conditions are poor (cold and dry) the tree ring is narrow. Scientists looks at the size of the rings to evaluate climate.
How do historical sources allow us to identify climate?
Written sources such as diaries or newspapers and artistic sources such as paintings or photos help scientists identify what climate was like at the time
Define greenhouse effect
The impact on the earths atmosphere as a result of greenhouse gases being released and making the earth warmer
Name 4 actions which produce carbon dioxide
Deforestation, driving cars, factories, electricity
Name 2 actions which produce methane
Farming(rice and cows) and landfill
Name 3 actions which produce nitrous oxide
Fertiliser, factories, flying aeroplanes
Name an action which produces CFCs
Using fridges or aerosols
What happens to UV radiation?
It is emitted by the sun (short wave) and about half of it is absorbed by the surface and warms it but some is reflected by the earths surface
What happens to IR radiation?
It is emitted by the earths surface (long wave) and is more difficult to escape the atmosphere so most is absorbed by the earths surface
How are crop yields affected by climate change?
Crop yields will decrease due to increased drought. This refers to how much people in an area are able to produce.
How do retreating glaciers affect people?
Causes the Gulf Stream to be diverted further south which would lead to colder temperatures in the region of Western Europe
How does rising sea level affect people?
This poses severe problems for people living on low lying islands because they are at risk of flooding
How do extreme weather events affect people?
Could be at risk of flooding
How does declining arctic ice affect people?
Boats can pass through the arctic which has positive affects on the economy as companies are able to trade goods and cruises can bring in money through tourism
Describe the formation of a cyclone
Storms move over hot oceans (26.5 degrees at least) and the storm and ocean surface’s hot air combines and begins to rise (creating low pressure), coriolis force causes the storm to spin, rising warm air causes pressure to decrease at higher altitudes, air rises faster to fill the low pressure drawing more warm air in so cooler drier air sinks, the storm moves over the ocean picking up more warm air and wind speeds increase
Define Coriolis force
An apparent force that is a result of the earths rotation and deflects moving objects to the right in the northern hemisphere and left in the southern
Why do some cyclones dissipate? 2 reasons
Without warm surface waters hurricanes cannot survive as this is their fuel (when they reach land or cold waters), when they run into other weather systems and winds are blowing in different directions
What is the Saffir-Simpson scale?
A 1-5 rating hurricane scale based on the hurricanes present intensity, gives an estimate of the hurricanes potential property damage and flooding
Name 9 characteristics of an area vulnerable to a cyclone
Located between 5-30 degrees north or south of the equator, next to an ocean of 26.5 degrees or hotter, has an uneducated population, unable to afford defences and warning systems, flat low lying relief, poor quality buildings and infrastructure, lots of people working in agriculture, high population density, has few resources
Name 5 hazards of cyclones
Storm surges, intense rainfall, heavy winds, landslides, coastal flooding
Identify 6 effects on people due to cyclones
Loss of life, injury, damage to homes, loss of property value, outbreak of health problems, less water availability
Identify 8 impacts of cyclones on the environment
Damage to buildings, water can become polluted, widespread stripping of forest cover, reshaping a coastal landscape, earth enters streams as sediment, structural changes to wooded ecosystems, roads blocked due to fallen debris, power lines come down
Identify 4 effects on people of hurricane Katrina
1833 died, 1 million homeless, 15 million affected, $135 billion in costs
Identify 2 effects of hurricane Katrina on the environment?
80% of the city flooded, cotton and sugar cane crops destroyed
Identify 3 effects of cyclone Aila on people
190 died, 750,000 homeless, 3.5 million people affected
Identify 3 effects of cyclone Aila on the environment
The delta was flooded with salt water, 59,000 animals killed, sickness and typhoid spread through flooding
How does weather forecasting prepare an area for a cyclone?
Weather is forecasted using atmospheric pressure. Low atmospheric pressure suggests the formation of a cyclone
How do warning systems help prepare an area for a cyclone?
People who live in cyclone-prone areas are regularly given information about how to be prepared via TV, radio, internet, phones
How does satellite technology help respond to a cyclone?
Tracks the eye of the cyclone after forming on a satellite image
How do evacuation strategies help respond to a cyclone?
Moves people out of vulnerable areas
How do storm surge defences help respond to a cyclone?
Prevent storm waves coming inland
How many phones do Bangladesh and USA have per 100 people?
Bangladesh 50, USA 103
How many satellites does Bangladesh own and how many does the USA?
Bangladesh 0 - has to borrow from China and Japan which costs $12 million a year, USA 20 however they are aging and one didn’t work in October 2012 when hurricane sandy was developing
Compare storm defences used by Bangladesh and the USA
Bangladesh’s do not cover the whole coast, the USA’s collapsed during hurricane Katrina
What is the composition of continental crust?
What is the composition of oceanic crust?
What is the density of oceanic crust?
What is the density of continental crust?
Name 2 hazards of a shield volcano
Lava flows, volcanic gases (e.g carbon dioxide)
Which two places are shield volcanos found?
Divergent, hot spots
Name 4 characteristics of a composite volcano
Andesite magma, lava is viscous, steep sloping sides, vent lava has high gas pressure and is explosive
Name 7 hazards of a composite volcano
Pyroclastic flow, ash, gases, mud flows, landslides, falling rocks, lava
Which plate boundaries do composite volcanoes form at?
Convergent destructive (oceanic-continental)
What happens at a convergent (continental-continental) plate boundary?
Two plates of continental crust move towards each other, resulting in a slow collision and causing intense folding of the land (fold mountains are formed). If the folded crust breaks pressure is released as seismic waves causing an earthquake.
Example of a convergent (continental-continental) plate boundary
Indian & Eurasian Plates
What happens at a convergent (continental-oceanic) plate boundary?
Two plates move towards each other and the oceanic plate becomes subducted beneath the continental into the mantle as the continental is less dense; the plate melts making andesite magma which escapes to form composite volcanoes. Sea water is dragged down which makes the magma less dense
Example of a convergent (oceanic-continental) plate boundary
South American & Nazca plates
What happens at a divergent plate boundary?
Two oceanic plates move apart on the sea floor and magma rises, cools and solidifies in the gap to make new oceanic crust. Convection currents in the mantle force up the newly formed oceanic crust, which is less dense, to form a mid ocean ridge. Magma rises in fissures between the plates to form volcanoes
Example of a divergent plate boundary?
Eurasian & North American plates
What happens at a conservative plate boundary?
Two plates slide past each other, getting stuck due to friction and pressure builds. Eventually this pressure is released when the plates jerk past each other as seismic waves causing an earthquake
Example of a conservative plate boundary
North American & Pacific plates
What is a hotspot volcano?
Volcanic regions in the middle of a plate fed by underlying mantle that is anomalously hot compared to its surroundings
How do hot spot volcanoes form?
A hot plume of magma rises through the mantle and burns through the crust causing runny basalt lava to spread across the sea floor, the lava from many eruptions creates an active shield volcano
What happens to hot spot volcanoes as a result of plate movement?
The plates movement carries the shield volcano with it so the mantle plume breaks; disconnected the volcano from magma and declaring it extinct. The mantle plume continues the same process but inactive volcanoes erode to form seamounts
Name 4 characteristics of a shield volcano
Contains basaltic lava, low explosivity fountaining, gentle sloping sides, wide base
The location where the earthquake begins
The point on the earths surface located directly above the focus
Identify 5 primary effects of Haiti’s earthquake
316,000 died, 1.5million homeless, all 8 hospitals collapsed or badly damaged, port at port-au-prince damaged, electricity and water and sanitation badly disrupted or destroyed
Identify 4 secondary effects of Haiti’s earthquake
Cholera spread through squatter camps, economic losses due to loss of tourism and factories, looting and crime increased, economic cost between $7-14billion
Name 4 reasons for differences in the impacts of Haiti’s and Japan’s earthquakes
The GNI per capita is much higher in Japan than Haiti, Haiti is developing whereas Japan is developed, earthquake was very shallow in Haiti, epicentre was close to the coast in Haiti
Describe short term relief earthquake management in Haiti
The USA and Dominican Republic provided food, water, medical supplies and temporary shelters. Uk disaster emergency committee raised £100million for emergency aid
Describe emergency services response to earthquakes in Haiti
Lack of trained emergency services
Describe preparation for earthquakes in Haiti
Few buildings were earthquake proofed
Describe predictions for earthquakes in Haiti
None within Haiti
Describe short term relief for earthquake management in Japan
People keep emergency kits of water, food, a torch and radio in their house
Describe emergency services response to earthquakes in Japan
Soldiers and rescue workers responded to the crisis
In what 2 ways does Japan prepare its population for earthquakes?
Disaster prevention day on the 1st September every year, television and radio stations inform the public of earthquake risk
Identify 5 primary effects of Japan’s earthquake
667-1479 deaths due to collapsed buildings, electricity lost to Fukushima nuclear power station, electricity and water and sewage disrupted, Fukushima dam burst, reclaimed land in Tokyo suffered liquefaction
Identify 4 secondary effects of Japan’s earthquake
Over 17,000 deaths by tsunami, 56 bridges collapsed due to tsunami, $300billion cost, 1.2 million buildings damaged due to tsunami
Explain how a tsunami is formed
Eventually after becoming subducted beneath the continental plate for many years, the oceanic plate will rebound and release tension as an abrupt movement - a sea quake. This displaces the water column as the sea bed has moved some metres upward. Once the water column collapses, it travels towards the coast, beginning as a small wave but the waves increase in size after their energy is compressed on hitting shallow water (wave shouling occurs)
What is the Richter scale?
A logarithmic scale (every whole number increase represents an earthquake ten times greater) which measures the strength of earthquakes
Explain convection currents
The core gives out heat due to radioactive decay which causes the outer core and mantle’s magma to move, where plates move away from each other a ridge forms and where plates move toward each other a trench forms. At the surface the convection current moves the tectonic plates in the crust and magma flows back to the core to be reheated
What are ocean currents powered by?
Wind resulting from atmospheric circulation cells or density differences due to differences in water temperatures and salinity
How often does the energy radiated by the sun changed?
Over an 11 year cycle
How can asteroids hitting earth affect climate change?
Cause huge fires which releases massive amounts of carbon dioxide, warming the planet
What percentage of Japan’s coastline has sea walls and how high?
40%, 10m high
How are buildings strengthened for earthquakes? 6 ways
Installing a ring beam (band of concrete) at roof level stops walls falling outwards, very strong framework in skyscrapers, strengthening walls, making foundations from rubber and steel which move slightly, digging deeper foundations, reinforcing gas and water pipes so they don’t break
How does Japan earthquake proof its buildings?
Built to move with the quake by using rubber and steel foundations
What is a cheap way to make buildings more earthquake resistant in the developing world?
Add diagonal braces which reduce movement
What material are buildings usually made out of in developing countries?
What 6 things need to happen after an earthquake?
Trained volunteers to help the injured and to clean away debris, clean water to prevent spread of disease, plan to evacuate area if needed, food because often shops and roads have been damaged, radio communication because phones may not work, medical help to care for injured people
How are composite volcanoes formed?
Eruptions of viscous, sticky lava and ash which don’t flow far
How are shield volcanos formed?
Formed by eruptions of thin runny lava which flows a long way before solidifying
How do shield volcanos erupt?
Frequently but not violently
How do composite volcanoes erupt?
Infrequently but violently including pyroclastic flows (mix of ash, gases and rock)
Why are composite volcanos more dangerous to humans than shield volcanos?
Shield volcanos contain basaltic magma which flows smoothly and is not full of gas whereas composite volcanic eruptions involve andesite magma which contains a lot of silica which clogs up the volcanic vent so pressure builds in volcano along with large amounts of gas that make it explosive and this leads to violent eruptions
Why did Hurricane Katrina cause so much damage? 5 reasons
New Orleans levee system was old and hadn’t been sufficiently maintained, pumping systems flooded and failed to work, highways out of New Orleans jammed, public transportation not used, shelters did not have enough food
What 4 improvements have occurred since Hurricane Katrina and how much did they cost?
Cost $14billion. City’s 200km of levees been made much higher and stronger, city’s 78 floodwater pumping stations have been made flood proof, new funding spent on search and rescue teams, city residents now get evacuation updates by text messsges
What does the lithosphere refer to?
Crust and uppermost solid mantle
What is the aesthenosphere?
A solid but ‘plastic’ layer of the mantle below the lithosphere which is under such high pressure that the rock flows
What impacts do storm surges have? 5 things
Drown people, sweep away buildings, contaminate agricultural land with salt, destroy crops, cause sewage spills that threaten public health through waterborne diseases such as typhoid
What are the wind speeds of a category 1 hurricane?
What is the pressure in millibars of a category 1 hurricane?
980 and over
What is the storm surge in metres for a category 1 hurricane?
What is the wind speed for a category 2 hurricane?
What is the pressure in millibars for a category 2 hurricane?
What is the storm surge of a category 2 hurricane?
What is the wind speed of a category 3 hurricane?
What is the pressure in millibars of a category 3 earthquake?
What is the storm surge of a category 3 earthquake?
What is the wind speed of a category 4 hurricane?
What is the pressure in millibars of a category 4 hurricane?
What is the storm surge of a category 4 hurricane?
What is the wind speed of a category 5 hurricane?
252 or higher km/h
What is the pressure in millibars of a category 5 hurricane?
Less than 920
What is the storm surge of a category 5 hurricane?
Over 5.7 meters
What damage does a category 1 hurricane do? 2 things
Trees lose branches and power lines come down
What damage does a category 2 hurricane do?
Roofs and windows damaged, coastal flooding, trees blown over
What damage does a category 3 hurricane do? 2 things
Structural damage to buildings, flooding over 1m up to 10km inland
What damage does a category 4 hurricane do? 2 things
Major devastation - destroys buildings and floods up to 10km inland
What damage does a category 5 hurricane do? 2 things
Catastrophic - destruction up to 5km above sea level, mass evacuation needed
Which three things cause cyclones to intensify?
When water temperatures are over 26.5 degrees, low wind shear (winds direction and speed does not change), high humidity
How much had average global temperature increased as a result of global warming?
in 2015 was 1 degree above average global temp in 1850-1900
Why can projections for future global temperature rises and future sea levels not be accurate?
The atmosphere and oceans are highly complex systems so computer models cannot always predict how they will respond, for example oceans have absorbed more heat than was expected and some natural events are hard to predict for example volcanos can cause atmospheric cooling and the sun can enter a cooler phase, affecting global temps
How much did the oceans warm by per decade between 1971 and 2000?
How much did sea levels rise globally in the 20th century?
How much less of the sea does the arctic sea ice cover each decade?
How much more common are heat extremes than a century ago?
Five times more common
How many cyclone warning volunteers are there in Bangladesh?
How does Bangladesh use weather forecasting to manage cyclones?
Bangladesh’s Meteorological Department issues forecasts and warnings on TV and radio however few people outside Dhaka have access to these
What are evacuation strategies like in Bangladesh?
3500 cyclone shelters which take 5000 people each however death rates are double when there are no shelters so more are needed
What are storm surge defences like in Bangladesh?
Embankments built to protect against storm surges however it is impossible to protect the whole coastline because it is 400km long and there are thousands of km of low lying coastline
What is weather forecasting for cyclones like in the USA?
National Hurricane Center in Miami issues forecasts and educated people
What are evacuation strategies like in the USA?
In Florida towns and cities like Fort Myers are classified into risk zones so only those that need to be evacuated are and this stops the system being overwhelmed , the poor and elderly are left behind
How beneficial are storm surge defences in USA?
Many embankments such as New Orleans however these xollapsed during Hurricane Katrina causing flooding and deaths of people who felt safe
When and why did Haiti’s earthquake occur, what was it’s magnitude?
12th January 2010, a 7.0 earthquake on the Richter scale occurred due to the conservative boundary between the North American and Caribbean plates
When and why did Japan’s earthquake occur, what was it’s magnitude?
11th March 2011 due to the convergent plate boundary between Pacific and Eurasian plate, 9.0