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global hazards Flashcards

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1
Q

What is the global circulation system?

A

The movement of air around the globe. It controls temperature, influences precipitation and creates climate zones.

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2
Q

What is low pressure ?

A

Warm air rises and creates an area of low pressure. As it rises, it cools, condenses and creates clouds (precipitation)

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3
Q

What is high pressure?

A

As air cools down, it will start to sink bc itā€™s denser. Sinking area creates high pressure as the air travels downwards, it becomes warmer and drier. (clear blue skies)

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4
Q

What is wind?

A

Air moving from high pressure to low pressure.

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5
Q

What is the order of cells from the equator?

A

Hadley cell, ferrel cell and polar cell

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6
Q

What happens in the hadley cell?

A

Air circulates around hadley cell
Air at equator warms, becomes less dense, and condenses to form clouds
Forms a low pressure belt + area of high rainfall
As air reaches troposphere, moves out to 30 degrees North and 30 degrees South of equator.
Air cools, becomes denser and sinks
Clouds donā€™t form results in area of high pressure belt
Air now moves from high pressure to low pressure

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7
Q

What are trade winds?

A

Winds that move back towards equator

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8
Q

What are westerlies?

A

Wind that moves back towards higher latitudes.

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9
Q

What happens in a ferrel cell ?

A

Warm surface winds from 30 degrees North and 30 degrees South meet cold air from the poles at 60 degrees North and 60 degrees South.
Warm air is less dense, rises above cold air into atmosphere + creates low pressure belt
Warm air rises, cools, condenses and forms clouds (high rainfall created)
Air reaches the troposphere, some air moves back towards the equator and some moves towards the poles.

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10
Q

What happens in polar cell?

A

Air from 60 degrees North + 60 degrees South of equator moves to pole
As it does this, air cools, becomes denser + sinks back towards surface
At 90 degrees North + 90 degrees south of equator +creates high pressure +little rainfall
Air, once it has sunk towards surface, starts to move back towards equator via surface winds

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11
Q

What are the three types of rainfall and where do they occur?

A

Convectional rainfall - tropical rainforests
Relief rainfall - mountains
Frontal rainfall - common in UK

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12
Q

What is relief rainfall?

A

When wind gets to mountains, the warm air is forced to rise. Leads to cooling, condensing and precipitation on the windward side of the mountain. When the air descends on the leeward side it will be dry.

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13
Q

What is frontal rainfall?

A

When warm air meets cool air, called a front. Warm air is forced to rise over cold air and clouds are formed. Eventually there is a steady rain.

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14
Q

What is convectional rainfall?

A

Sunshine warms up the grounds and air above it. Pockets of warm air rise. At high altitudes, air cools and condenses to form clouds when rain falls, it can be heavy.

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15
Q

What is the albedo effect?

A

How much a surface reflects or absorbs sunā€™s rays eg. polar ice has a high albedo reflecting more heat and makes poles colder. Tropical rainforests have a low albedo and absorbs more heat.

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16
Q

What is cloud cover?

A

Cloudā€™s reflect the sunā€™s ray and reduce the amount of solar radiation that reaches the earthā€™s surface. It is strongest at the equator but thick clouds reduce the amount of radiation reaching the surface.

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17
Q

How do ocean currents affect rainfall?

A

Current in the ocean moves heat eg. warm water from the caribbean and warms the west coast of England.

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18
Q

How does altitude affect temperature?

A

As air rises to higher altitudes, it is subjected to less pressure, expands and cools.

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19
Q

Elaborate on climate in Death Valley (USA) ?

A

Extremely hot and dry bc it is in the subtropical climate belt. Also has low albedo + is in the rain shadow of the Sierra Nevada mountain range.

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20
Q

Elaborate on the climate in Vostok (Antarctica)?

A

Coldest place on Earth - temperatures as low as -99 degrees . It is in a polar cell so high pressure + stable dry weather w/ few clouds to trap any heat. Sunā€™s energy is reflected back to space - high albedo. Dry bc air is so cold that it holds little water vapour.

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21
Q

Elaborate on climate in Khasi Hills (Meghalaya, India)?

A

Wettest place on Earth w/ avg annual rainfall of 11872mm in tropical zone where HAdley cells meet giving low pressure but having hot + wet weather instead. Located right near the equator where the sunā€™s rays are strongest. Khasi hills are part of a low mountain range where clouds blown in from Bay of Bengal + travel over land of Bangladesh. When clouds reach hills, forced to rise rapidly results in heavy rainfall.

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22
Q

Elaborate on climate in Wellington (New Zealand)?

A

Located in a temperate zone where the climate is mild and wet. Often gets frequent strong notherlies so has windy weather. Most of the time results in Wellington being the windiest city on Earth.

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23
Q

Elaborate on climate in Atacama (Chile)?

A

Lies on the tropic of capricorn. In the rain shadow of the Andes mountains and also has cold ocean currents flowing alongside it, so no moist warm to form clouds. In a subtropical zone where cold air sinks and loses moisture in a hot and dry climate.

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24
Q

Elaborate on climate in Lut Desert (Iran) ?

A

Home to the record of highest temperature bc of intense sunshine due to it being near the equator and the surface area absorbs heat. Also has low albedo bc has lots of dark pebbles that absorb heat well.

25
Q

Describe distribution and frequency of tropical storms and drought ?

A

Most tropical storms occur between 5 and 20 degrees North and south of the equator
Frequency of storm since 1995 has mostly stayed the same
Areas most at risk from drought is central southern africa, middle east, australia, eastern South america and parts of North South America
Distribution changed since 1950, more droughts in Africa, Asia + Mediterranean, fewer droughts in America, Russia
Frequency of drought has not altered much

26
Q

What is drought?

A

Drought is a prolonged period of weather that is drier than usual

27
Q

How is la nina caused?

A

Trade winds are stronger

Surface temperatures decrease

28
Q

CAn u elaborate on la nina conditions?

A

Strong trade winds carry moist air across the pacific ocean
Warm water on east coast of Asia and australia, cooler water on West coast of south america
Convection currents form above the warm water moving westwards
Results in heavy rain + thunderstorms in the Western Pacific.

29
Q

Causes of the UK drought? (Less rainfall, warmer temperatures, dryer soils, high water usage and climate change)

A

Less rainfall between march 2010 and May 2012, the areas affected by drought received only 55%-95% of usual rainfall bc unusual wind patterns bought dry winds from Europe in the East rather than the usual wet winds blowing from the Atlantic in the west,
Warmer temperatures: Uk weather was also warmer than usual so more water evaporated from reservoirs than usual + soil dried out
Dry soils - soils so dry that from lack of rainfall that when it did rain water couldnā€™t absorb into soil.
High water usage - large amount of water is used in everyday lives + waste quite a lot thru leaky pipes - 1.7 billion litres daily
Climate change - long term cause - loss of ARctic sea ice. Officials made links between melting sea ice and new water patterns.

30
Q

Consequences of UK drought?

A

Farming : Farmers had difficulties finding water for crops + livestock bc of water shortages. Dry soils also made it difficult to harvest crops in autumn of 2011.
Environmental damage - Dry areas of moor land caught on fire with many wildfires breaking out across South Wales. Surrey, Scottish borders. River water was also used to raise the quantity of water in some areas which meant it reduced river levels and caused damage to animals and plants
Wildlife: Tadpoles, toads and rare species eg. Great crested newts were at risk of dying if ponds dried out. Ponds and streams that were at risk of drying out affected the population of dragonflies since it affected the development of the aquatic insect.

31
Q

Responses to drought 2012?

A

Permits granted to water companies that allowed them to extract water from rivers
Conservations of ramining water by issuing hose pipe bans
Campaigns that persuaded ppl to use less water in their day to day lives
Environment agency removed fish from ponds + placed them in less affected waters

32
Q

Future responses to Drought?

A

Experts called for the government and water companies to invest more money into new technology that can cope with climate change and deliver water to a growing population.

33
Q

List impacts of hurricane katrina?

A

Oil facilities were damaged + petrol prices rose in Uk and USA.
1 million people made homeless + 1200 people drowned on floods
People sought refuge in Superdome stadium where conditions were hygienic, shortage of food + water. Looting took place. Tension was high + mANY felt uncomfortable or unsafe and vulnerable
Damage cost $100bn estimated.
Levees were overwhelmed in New Orleans and thus 80% of city was flooded.

34
Q

List responses to Hurricane Katrina?

A

$50 billion in aid was given by the government.
The UK government sent food aid during the early stages of the recovery process.
The National Guard was mobilised to restore and maintain law and order in what became a hostile and unsafe living environment.

35
Q

What happens at a shield volcano?

A

The mantle rises to the surface as the plates pull apart. This lowers the pressure on the hot rock which partially melts and becomes runny. It doesnā€™t trap gases and nothing plugs the volcano so eruptions are gentle. It surfaces as runny lava. This flow quickly and cools to form a gently sloping shape.

36
Q

What happens at a composite volcano?

A

The partially melted mantle that rises up is viscous (sticky). It contains trapped seawater and hot gases. This builds up pressure when it is released suddenly, steam and dangerous gases erupt violently from the volcano. The thick lava cools quickly so it flows slowly creating steep slopes. Ash also escapes from the volcano and lands on the slopes. This alternate layering of lava and ash creates composite volcanoes. Sometimes cooled rock forms a plug at the top of the main vent. This leads to an enormous build up of pressure before the next eruption which will be more explosive.

37
Q

State characteristics of composite volcanoes?

A

Are formed on a destructive plate margin
Are formed by eruptions of viscous, sticky lava and ash that doesnā€™t flow far
Have sleep sloping sides and a narrow base
Are made up of layers of thick lava and ash
Contains andesitic magma which is less hot than basaltic magma but which contains lots of silica and gas
Erupt infrequently but violently including pyroclastic flows (mix of gases, ash and rock)

38
Q

Causes of earthquakes?

A

Caused when plates stick, huge pressure can build up. When plates break free/one plate gives way, energy released causes an earthquake between Earthā€™s surface at focus. Fast waves of energy (seismic waves) spread out from focus through the rock. They reach the surface at the epicentre directly above the focus.

39
Q

Where did the Haiti Earthquake hit?

A

Capital city of Haiti, Port Au Prince

40
Q

How much did it cost Haiti?

A

$10bn USD

41
Q

Why was Haiti Vulnerable? (geographical location, buildings + location hit)

A

Haiti sits on a boundary between the Caribbean plate and north american plate (conservative boundary) so the land masses slide past each other but there can be friction built up which leads to huge pressure released causing an earthquake.

Erahwauke hit a densely populated area - the capital city Port Au prince where homes had substandard building quality on top of hillsides which had no foundation so were more likely to collapse - both factors contributing to a higher number of casualties + injuries and more homeless ppl.

42
Q

Why was HAiti so vulnerable (debt + medical equipment + economy)?

A

Haiti was also recovering from debt to France since it was one of their colonies so was left on an economy relying on sugar which is a primary good which prices fluctuate extremely daily - also relies on family/ relatives abroad transferring money which means that the city has poor infrastructure with dirt tracks for roads and poorly equipped medical / emergency services so resulted in a poor response?

43
Q

List some primary impacts of the Haiti earthquakes?

A

230000 deaths
300000 injured
Water systems totally destroyed
Power lines destroyed making rebuilding harder
Roads and bridges destroyed
Schools, hospitals and police stations destroyed
Large number of government buildings destroyed making responses harder to coordinate

44
Q

List some secondary effects of the earthquake?

A

1.5 million homeless and had to sleep on the streets
Looting, theft and violence increased
Stress and trauma negatively affected mental health
No food or basic clothes
Damaged water supply caused the spread of disease such as cholera

45
Q

What were the long term responses to the Haiti Earthquake? (microcredit scheme, housing + infrastructure)

A

Gave out small loans so families could open shop again and got stock so families could become financially independent
Retraining ppl to rebuild their homes to be more earthquake resistant

46
Q

List immediate responses to the Haiti earthquake? (camps, raising money, medcā€™s response, food)

A

NGOā€™s such as Oxfam raised money and sent food
MEDCā€™s sent rescue teams, soldiers and equipment.
Citizens in MEDCā€™s raised over $100 million including a charity single
NGOs + Haiti government made temporary camps on the edge of cities to house ppl
Oxfam opened up canteen to feed people

47
Q

What was it like in Haiti six months after the earthquake?

A

Ppl still had to live in tents in the camps that NGOā€™s set up bc ppl lost their means to make a living and were unable to buy a house/get a job since no-one was trading goods + services

48
Q

List techniques to mitigate effects of earthquakes ? (building techniques)

A

Constructing earthquake proof buildings - can be expensive but can save many lives - can be made earthquake resistant by using stronger + more flexible materials (steel) + can put shock absorbers into foundations so buildings move rather than collapse in earthquake + strong safety glass can be used in windows + gas and electricity pipes can be installed that switch off automatically in an earthquake. LEDCā€™s buildings can have secure foundations to hold them together but have a light roof so it wonā€™t hurt ppl if it falls.

49
Q

List techniques to mitigate effects of earthquakes? (education)

A

Drop, cover, hold : ppl taught to drop, cover head + neck/ crawl under table + hold. Taught not to run outside + stay clear of windows/objects that may fall.
Ppl less likely to panic when hazard strikes so will reduce the risk of chaos and disorganisation
Training: countries can train ppl on how to evacuate so they get out of danger quickly. Eg. Japan National Earthquake Day on Sept 1st - even tourists are given information packs to ensure they are prepared + taught to make earthquake survival kits that contain food, water , torch and radio.

50
Q

List techniques to mitigate effects of earthquakes? (planning)

A

Town planners can set up firebreaks gaps between buildings that are planned to stop fires spreading out of control + emergency supplies of medicine, tents, foods + blankets can be stored in warehouses so they are readily available when needed. Governments can also encourage ppl to take our insurance so that their homes + possessions can be replaced. Emergency services can also be trained carefully to make sure they prepare for an earthquake to practise setting up evacuation routes + setting up emergency camps for homeless ppl/ rescue ppl from collapsed buildings . Less chaos + disorganisation when hazards happen.

51
Q

List techniques to mitigate effects of earthquakes? (prediction)

A

Impossible to actually predict earthquakes +when they happen however there are clues, small tremors happen before major earthquakes + cracks may appear in rocks. Countries can invest in seismic monitors to detect early activity. Can map old earthquakes and seismic gaps ( areas along known faults that havenā€™t experienced activity for a long time + most likely where pressure built up) Eg. Japanā€™s warming system (4000 seismometers) detect early P waves - trigger early warning systems, TV + Radio programmes automatically broadcast earthquake warnings + get automatic text messages to phones. Can be ineffective as warnings go out after the earthquakes hit.

52
Q

State characteristics of a shield volcano?

A

are found on constructive plate margins and hotspots

are formed by eruptions of thin runny lava which flows a long way before it solidifies

have gently sloping sides and a wide base

contains balsaltic magma which is very hot with low siicia and gas content

erupt frequently but not violently

53
Q

What is a shallow focus earthquake?

A

an earthquake that starts within 70 km of the earthā€™s surface. they are usually small and cannot be felt but can cause damage over a large area

54
Q

what is a deep focus earthquake?

A

an earthquake that starts 70 - 100 km below th earthā€™s surface. they can be very powerful but affect only a small area.

55
Q

What are sesimic waves?

A

energy release by the earthquake

56
Q

what is an epicentre?

A

the point on the earthā€™s surface directly above the focus

57
Q

what is the focus?

A

point in the earthā€™s crust where the earthquakes happen

58
Q

what happens at a hotspot margin?

A

a hot plume

geography (3 decks)

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