Global Hazards Flashcards
REMEMBER TO ADD BOSCASTLE AND BIG DRY AFTER JAN
1
Q
What happens at the equator in terms of atmospheric circulation?
A
Two converging air masses meet(both hadley cells) and rise, forming a low pressure system and creating heavy rainfall at the equator.
2
Q
What happens at:
1. 30N
2. 30S
3. 60N
4. 60S
A
- High pressure system(Hadley+Ferrel)
- High pressure system(Hadley+Ferrel)
- Low pressure system(Ferrel+Polar)
- Low pressure system(Ferrel+Polar)
3
Q
What determines heat? Why? [2]
A
- Latitude; because of insolation
- Sun’s rays are concentrated at the equator, as opposed to spread out at higher points and lower points.
4
Q
What determines dryness? Why? [3]
A
- Pressure belt
- High pressure belt means low precipitation
- Low pressure belt means high precipitation
5
Q
What are Westerlies? What are Trade Winds?
A
- Westerlies are winds that blow towards the poles.
- Trade winds are winds that blow towards the equator.
6
Q
What are the 4 climate zones?
A
- Polar; cold all year round
- Tropical; High temperatures all year round and high precipitation
- Temperate; Moderate summers and winters
- Arid; hot/warm and dry
7
Q
What are the coldest and hottest temperatures ever recorded and where were they?
A
- 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
8
Q
What weather extremes are associated with wind? [3]
A
- 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
9
Q
What weather extremes are associated with temperature?[3]
A
- 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.
10
Q
What weather extremes are associated with precipitation? [3]
A
- 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
11
Q
What is the distribution of tropical storms? [2]
A
- A lot of tropical storms occur in East Asia in late summer and Autumn
- NO TROPICAL STORMS ON EQUATOR
12
Q
What is the frequency of tropical storms? Why? [2]
A
- 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
13
Q
What is the distribution of droughts? [2]
A
- Typically affected by rainfall and demand for area; High pressure areas get more frequent droughts
- More in Africa, Asia, and the Mediterranean
14
Q
What is the frequency of droughts?
A
- 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.
15
Q
How are tropical storms formed? [5]
A
- 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)
16
Q
How can tropical storms cause damage? [3]
A
- 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
17
Q
What is El Nino? [4]
A
- 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
18
Q
What is La Nina? [4]
A
- 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
19
Q
What are the 4 layers of the Earth?
A
- 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)
20
Q
What are convection currents and what do they affect? [2]
A
- 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
21
Q
What is a destructive plate boundary? [5]
A
- 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
22
Q
What is a conservative plate boundary? [4]
A
- 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
23
Q
What is a collision plate boundary? [4]
A
- 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
24
Q
What is a constructive plate boundary? [4]
A
- 2 plates move apart, so magma rises to fill the gap
- This magma cools and forms new crust
- Forms shield volcanoes
- Example: Eyjafjallajokull
25
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)
26
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.
27
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
28
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
29
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
30
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
30
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
31
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
32
What caused the Haiti Earthquake?
A conservative plate boundary between the Caribbean and North American plate.
33
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
34
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)
35
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
36
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
37
When was the Boscastle flood?
16th August 2004
38
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.
39
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
40
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
41
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
42
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.
43
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
44
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%
45
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.
46
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
