Global Hazards Flashcards
REMEMBER TO ADD BOSCASTLE AND BIG DRY AFTER JAN
What happens at the equator in terms of atmospheric circulation?
Two converging air masses meet(both hadley cells) and rise, forming a low pressure system and creating heavy rainfall at the equator.
What happens at:
1. 30N
2. 30S
3. 60N
4. 60S
- High pressure system(Hadley+Ferrel)
- High pressure system(Hadley+Ferrel)
- Low pressure system(Ferrel+Polar)
- Low pressure system(Ferrel+Polar)
What determines heat? Why? [2]
- Latitude; because of insolation
- Sun’s rays are concentrated at the equator, as opposed to spread out at higher points and lower points.
What determines dryness? Why? [3]
- Pressure belt
- High pressure belt means low precipitation
- Low pressure belt means high precipitation
What are Westerlies? What are Trade Winds?
- Westerlies are winds that blow towards the poles.
- Trade winds are winds that blow towards the equator.
What are the 4 climate zones?
- Polar; cold all year round
- Tropical; High temperatures all year round and high precipitation
- Temperate; Moderate summers and winters
- Arid; hot/warm and dry
What are the coldest and hottest temperatures ever recorded and where were they?
- Coldest was in Antarctica(-89.2C) due to insolation and ice albedo
- Hottest was in Death Valley (56.7C) due to high pressure system and insolation
What weather extremes are associated with wind? [3]
- Trade Winds
- Katabatic winds(up to 320km/hr of wind flowing downhill)
- Jet streams(winds very high up in the atmosphere)
- Tornadoes(strong rotating winds) or tropical storms, causing house destruction
What weather extremes are associated with temperature?[3]
- Latitude(insolation)
- High pressure systems have less cloud cover as the air is sinking, so less light is blocked by clouds, so it’s hotter.
- Ice albedo also lowers temperature
- Ocean currents also carry more heat easily, so they have a warming effect.
What weather extremes are associated with precipitation? [3]
- Precipitation is much higher low pressure belts, so it is affected by rainfall
- Frontal: Warm air rises over cool air, cools and condenses, and precipitates
- Convectional: Air from sea rises, expands, cools, condenses, and precipitates
- Relief: Air is forced to rise over land, and condenses and precipitates
What is the distribution of tropical storms? [2]
- A lot of tropical storms occur in East Asia in late summer and Autumn
- NO TROPICAL STORMS ON EQUATOR
What is the frequency of tropical storms? Why? [2]
- 2007 found increase in observed hurricanes over the past century, but no overall trend
- Likely due to increased technology so more can be picked up
What is the distribution of droughts? [2]
- Typically affected by rainfall and demand for area; High pressure areas get more frequent droughts
- More in Africa, Asia, and the Mediterranean
What is the frequency of droughts?
- Predicted persistent droughts in next 50 years, and Climate Change + Global Warming will increase temperature
- Therefore higher chance of droughts, but currently varied frequency per year.
How are tropical storms formed? [5]
- They form between 5-15N and S of the equator, when sea temperature is above 27C
- Warm ocean means there is a lot of moist air, so it rises, cools, and condenses into droplets, forming huge cumulonimbus clouds.
- These droplets combine to fall as rain
- Since the air has risen in the center, there is a low pressure system in the middle, causing high pressure areas to be pushed into it by trade winds
- This forms high speed rotating winds due to Earth’s rotation(Coriolis effect)
How can tropical storms cause damage? [3]
- Fast strong winds can launch projectiles into buildings, kill people, damage infrastructure, and block roads
- Storm surges; wind blows water over land, so huge waves and flooding is caused
- Large amounts of rain, which can cause flash floods, destroy crops
What is El Nino? [4]
- Warm water moves East due to weak trade winds, evaporating as it moves to SA
- This warm air rises above SA, forming a low pressure system there with lots of rainfall.
- Air then moves westwards via high altitude flow and sinks above Australia
- This forms a high pressure system there, with warm, dry conditions, causing droughts and fires
What is La Nina? [4]
- Very strong trade winds push water westwards towards the East Coast of Australia
- This forms a high pressure system in Australia, so air rises and cools and condenses there, causing flooding and extreme conditions of a normal year
- Air then moves eastwards via a high altitude flow, and sinks above South America
- This forms a high pressure system there and causes extreme weather conditions like droughts and fires there
What are the 4 layers of the Earth?
- Crust: can be Oceanic(dense, thin, made of basalt, 8km), or continental(less dense, thin, made of granite, 35km)
- Mantle(up to 4000C)
- Outer core(up to 6000C)
- Inner core(7200C)
What are convection currents and what do they affect? [2]
- The lower parts of the mantle are hotter than the upper parts, when they heat up, they become less dense, rise, cool, and sink in circular movements called convection currents.
- These cause tectonic plates to move
What is a destructive plate boundary? [5]
- When an oceanic plate meets a continental plate, the more dense oceanic plate sinks under the continental plate
- It then goes into the mantle, where it is subducted(sinks into the subduction zone) and destroyed
- Forms trenches, which can cause violent earthquakes if the plates get stuck
- Forms composite volcanoes
- Example: Tohoku Earthquake, Japan
What is a conservative plate boundary? [4]
- Two plates moving sideways past each other, and the jagged edges get caught due to friction
- Pressure builds up, so when they jolt, it is all released
- Causes earthquakes
- Example: San Andreas Fault OR HAITI EARTHQUAKE
What is a collision plate boundary? [4]
- 2 continental plate boundaries move towards each other, and collide
- Neither is forced below the other, so they are both forced upwards
- Creates fold mountains
- Example: Himalayas
What is a constructive plate boundary? [4]
- 2 plates move apart, so magma rises to fill the gap
- This magma cools and forms new crust
- Forms shield volcanoes
- Example: Eyjafjallajokull
What are hotspots? [4]
- Hotspots come from mantle plumes originating in the outer core, coming from heat from subducted rock
- These rise up and form volcanoes by hitting the surface of the crust
- As the tectonic plate moves, it drags the plume head, forming volcanoes as it goes along
- These are known as volcanic chains(Like the Hawaii volcano chain)
How does tectonic plate movement cause Earthquakes? [2]
- Energy is released into the focus from built-up pressure, releasing seismic waves
- These waves reach the surface at the epicentre.
What two types of Earthquakes are there? Where do they each occur?[4]
- Deep focus(70-700km below surface),rarer, which cause less damage as it spreads vertically
- Occur on destructive plate boundaries as they are triggered when the oceanic plate sinks
- Shallow focus(less than 70km below surface),more common, cause more damage as it is closer to the surface(so over smaller area)
- Occur on collision and conservative plate boundaries
How does tectonic plate movement cause volcanoes? [2]
- Partially melted mantle is viscous, and rises.
- It contains hot gases which build up pressure, so when it is released it erupts violently and cools quickly, forming steep volcanoes
What are the characteristics of composite volcanoes? [5]
- Acid, viscous lava
- Rare eruptions
- Violent eruptions
- Occur at destructive plate boundaries
- Cone-shaped/steeper
- Thinner layers of ash and lava(which sometimes forms a plug at the top of the volcano, building up enormous pressure, making the eruption even more explosive
What are the characteristics of shield volcanoes? [5]
- Basic, runny lava
- Frequent eruptions
- Gentler eruptions
- Occurs on conservative plate boundaries or hotspots
- Shallower/flatter
- Thicker layers
Name 3 ways technological developments can save lives in hazard zones.
- Early warning systems; people in Japan had 30 seconds to prepare, turn off utilities to avoid fires and leaks, find cover, stop delicate activities, etc.
- Computer controlled roof weights, cross-bracing to prevent twisting in buildings, shutters to prevent falling glass
- Seismometers and lasers to predict indications that an earthquake is likely
- Go-bags for preparation, education on earthquake safety
What are the details of the Haiti Earthquake? [3]
(Name the focus, magnitude, and date)
- 10-13km deep focus
- 7.0 on the Richter Scale magnitude
- 12th January 2010
What caused the Haiti Earthquake?
A conservative plate boundary between the Caribbean and North American plate.
What were the primary effects of the Haiti Earthquake? [4]
- 220,000 deaths
- Power lines cut, so no communications
- 106,000 homes destroyed(as builders took shortcuts)
- 80% of schools destroyed
- Damage to airport runways made it hard to transport aid
- Prison collapse led to escaped prisoners
What were the secondary effects of the Haiti Earthquake? [4]
- 2 million Haitians left without water(social)
- November 2010 Cholera outbreak(social)
- Stealing became an issue(social)
- Up to $8.5billion in damages(economic)
- 8 hospitals destroyed; INTENSE overcrowding in hospitals(social)
What were the immediate responses to the Haiti Earthquake? [3]
- Medecins Sans Frontieres sent to Haiti
- UN Search and Rescue teams saved 120 people in the following week of the Earthquake
- 10,000 NGOs involved: BAD because it was too disorganised and chaotic to provide efficient help
- World Food program sent food in planes, trucks
What were the long-term responses to the Haiti Earthquake? [4]
- Public donations endorsed by celebrities
- International Goverment aid pledges, like Florida Search and Rescue teams sent. and money to rebuild
- World Food Program sent food in planes, trucks(long-term because it went on for months)
- Earthquake drills and training provided to educate the population
- Cash for Work programs paying Haitians to clear rubble
When was the Boscastle flood?
16th August 2004
What where the place specific causes of the Boscastle flood? [2]
- Boscastle is in the Valency Valley, which is steep sided. It is also located on the confluence of 3 rivers (Paradise, Jordan and Valency), making it very prone to flooding
- Boscastle was built around impermeable rock such as slate and clay, which meant that much less rain was absorbed into the soil, so flooding was more likely.
- Boscastle also experienced heavy rain prior to the event, which meant that the ground was saturated and could carry less water. Knock-on effect to the impermeable rock point.
What were the impacts of the Boscastle flood? [4]
- 1000 residents and tourists affected
- 58 properties damaged, 6 completely destroyed
- Cost £2 million
- Damaged 25 of Boscastle’s businesses
- Destroyed tourism in Boscastle; 90% of it’s income is from tourism
- 4 bridges destroyed and washed away
- Trees uprooted and washed away
What were the immediate responses to the Boscastle flood? [3]
- Over 150 people airlifted to safety by 7 RAF helicopters.
- Police, Fire Brigade, and Coast Guard responded in minutes
- Temporary shelters put up for those evacuated
- Nationwide media coverage
What were the long-term responses to the Boscastle Flood? [3]
- River Jordan Channel Relief made wider
- 1850 tonnes of silt and debris cleared
- River banks and flood walls were raised
- New technology to help predict flood events more accurately
- £4.5 million dedicated to a flood prevention scheme
What were the causes of the Big Dry in Australia(2005-2008)? [2]
- High pressure system above Central Australia
- Australia is a large, relatively flat continent - moisture doesn’t penetrate deep into the interior
- Mainly caused by a strong El Nino year.
What were the social impacts of the Big Dry in Australia? [3]
- 13 dairy farms closed(only 6 survived)
- Water shortage led to a drop in agricultural production
- Rural areas had no water
- Rural suicide rate soared
- Mass migration into wetter areas
What were the economic impacts of the Big Dry in Australia? [2]
- Farmers had to sell water and cattle because they couldn’t afford to feed them
- Wheat production and exports dropped by 46%
- Food prices increased because Australia had to rely on imports
- Energy and water prices increased by 20%
What were the environmental impacts of the Big Dry in Australia? [3]
- River Murray dried up in places and was 50% below its normal level
- Grassland transformed to shrubland due to water starvation
- 70% of redgums died
- 6 million sheep died
- Drop in water levels meant less Hydroelectric power production, so coal had to be re-used for energy
- Loss of vegetation, wildlife, biodiversity, as well as more soil erosion and salinisation.
What were the responses to the Big Dry in Australia? [3]
- Government dedicated $10 billion to national water management scheme in 2007
- Government tried to control water usage more by introducing the national water database, which monitors water usage
- Drought resistant crops introduced
- Degraded and salt-affected areas were classified as retired to avoid additional water waste
- Irrigation methods updated to avoid over-watering