geography global hazards

Question 1

What are the three cells of air

Answer 1

Hadley, Ferrel, Polar

Question 2

What happens in the hadley cell?

Answer 2

Between 30-40 degrees N and S from equator. Trade winds blow from tropical regions towards equator in easterly direction. Trade winds meet near equator and warm rise forms thunderstorm storms, air flows to higher latitudes where it cools and sinks over subtropical regions.

Question 3

What happens in the ferrel cell?

Answer 3

Middle cell between 60 to 70 degrees, moves in opposite direction to the other 2 cells. Joins sinking air of hadley and travels at low heights to mid latitudes where is rises on border with cold air of polar cell. air flows back towards low latitudes in direction of equator.

Question 4

What happens in the polar cell?

Answer 4

Smallest and weakest cell, air sinks over highest latitudes at poles and flows to the lower latitudes.

Question 5

What happens in areas of high pressure? Where are they?

Answer 5

When air cools it gets dense and falls creating high pressure, happens at sinking air of polar and where the ferrel and hadley cell join

Question 6

What happens in areas of low pressure? Where are they?

Answer 6

Low pressure system occurs when atmospheric pressure is lower than surroundings area. When high winds and warm air rises, it cools and condenses to cause rain. Where air in hadley cells rises at equator, low pressure is created.

Question 7

What are the places of extreme weather(windiest, rainiest, coldest, hottest, driest)

Answer 7

Windiest place- common wealth bay Antarctica-240km/h
Rainiest- Cherrapunjy, Khasi Hills, highest rainfall in 1 month- 9300mm in July 1861, clouds blow from the bay of Bengaland rise at Khasi Hills creating rainfall.
Hottest- lut desert, Iran, highest temp-70.7C, strong sun on dark rocks make it hot, no one lives only tourists tropical climate.
Coldest- Antartica, lowest temp-89.2C, covered in while ice which reflects suns energy
Driest- Atacama desert, av. rainfall- 15mm, costal mountains block moust air from pacific so air is forced to condese on the other side

Question 8

Where are droughts mostly found?

Answer 8

located in areas such Africa south america india .

Question 9

Where are tropical storms mostly found?

Answer 9

Near the equator, 15 degrees N and S, East asia, east pacific 3+ and in Caribbean and madagascar 1-3

Question 10

What is the recipe for extreme weather?

Answer 10

ocean is 26.5C, Water depth=60+m deep, 5-15 degrees N/S of the equator

Question 11

Describe how a tropical storm is formed

Answer 11

1) ocean is 26.5 degrees, depth is 60m+ so ocean water starts to evaporate
2) warm air rises
3) causes low pressure which sucks air from trade winds. Winds spiral and absorb moisture from ocean
4) humid air forms storms
5) moist air cools and condenses releasing energy to make storm intense
6) Cool air sinks creating an area of clear conditions, eye of the storm

Question 12

What happens in an normal, el nino and la nina year?

Answer 12

Normal- trade winds blow west to peru, strong surface current near SA, SA- high pressure, descending air warm dry conditions, up welling cold water due to shallow position of thermocline winds pull water from water good for fishing. Australia- warm surface water, rising warm air so rain low pressure

El Nino- opposite of normal. SA- rising warm air so rain and floods, cold water blocked by warm water so fishing impacted, low pressure, rise of sea cause erosion and flooding. Australia - trade winds blow eat and weak, descending warm dry air warm surface currents reverse of to south america

La nina- more intense normal

Question 13

What is a drought?

Answer 13

period with lack of precipitation

Question 14

What is some backgroud info about murray darling basin?

Answer 14

14% of Australia land, 20% less rainfall fallen that long term average, generate 39% of Australia agriculture- grain, fruit and cattle

Question 15

What are the causes, impacts and responses to the murray darling basin?

Answer 15

Causes- human- too much water extracted from system. Environmental- unreliable rainfall climate change, high temp 0.08C warmer so 94% of rainfall evaporates to reservoir is dry and lack of water.

Impacts- suicide rates of farmers increase due to economic run negative impacts on agriculture, river systems dry up, dust storm, tourism affected, 1% of $640 b economy knocked off.

Responses- dams built so less water wasted imposing water use restrictions for lawns, and sprinklers, recycling water- ‘grey water’, tapping into underground water and developing desalination to make water drinkable.

Question 16

Explain the causes, impacts and responses to the flooding in cumbria flooding in 2015?

Answer 16

Causes- human- many building so lack of interception, pavements are impermeable to water builds up, man made bridges risk of collapsing and wont let water through man made changes to road which builds up pressure in water. Physical- climate change so more extreme weather, heavy rain and strong winds because of low pressure, high water levels in reservoir which overflow

Impacts- social- 43,000 homes power cuts, 40 schools closed, people swept away. Environmental- many landslides, vegetation destroyed, water quality affected, trees on bank ripped away, bridges collapsing. Economic- multi million pound defences wasted, extensive damage was £500 million

Responses- full national emergency 200 military and high volume water pumps, fire services called, £400,000 donated by public, volunteered to evacuate people from Carlisle

Question 17

What is a destuctive plate boundary?

Answer 17

2 plates push together and land is destroyed. Denser plate(oceanic plate sinks below to lithosphere, the less dense continental plate is above this is called subduction. A oceanic plate sinks it rubs and causes friction which melts the plate and creates magma which rises up through the cracks as volcanic eruption, very explosive. Also felt dye to friction between plates.
Eg. Oceanic Nazia plate subducted under South America plate.

Question 18

What is a conservative plate boundary?

Answer 18

Plates slide past each other either in same direction at different speeds to parallel to each other in opposite directions. 2 plates slip past each other, they will snap and build up pressure until they jolt pas each other and earth quake caused. Plates get jammed and rough edges cause extreme stress until one snaps.
Eg, the San Andres Fault.

Question 19

What is a collision plate boundary?

Answer 19

If 2 continental plates collide, neither one subducts as they are the same densities. The plates push together the material between the is caused to buckle and rise up forming fold mountains. Severe earthquakes.
Eg. Himalayas

Question 20

What is a constructive plate boundary?

Answer 20

Plates are separating by moving away from each other driven by convection currents in mountain.
Oceanic- causes partially melted magma to come up through fissure in oceanic crust. Non explosive and forms new crust when solidifies at the surface. Eg. Mid Atlantic ridge

Continental- partially melted magma rises and heats plates above it, This causes a buldge in the land.
As plates stretch they fracture along fault lines.
Eg. The great African rift valley

Question 21

What are the layer of the earth? Describe them

Answer 21

Inner core- centre, solid iron and nickel, 6000C, 2,500km wide
Outer core- like boiling hot sea of liquid metal, iron and nickel, 4030- 5730C, 2,200km thick
Mantel- rock melts to liquid, hot dense liquid rock (magma) which connects due due heat from core, 1,300C, 2,900km thick
Crust- solid rock shell, continent and Ocean sit on it, fragment into tectonic plates that float on mantel, continental and oceanic crust
Asthenosphere- top layer of mantel
Lithosphere- top layer of mantel and crust

Question 22

Describe the convection currents

Answer 22

Heat from core causes liquid to rise, it cools then falls back down, heat creates convention currents which cause plates to move.
Inner core is very hot caused by radioactive decay, gives off heat.

Question 23

Describe the cross-section of an earthquake

Answer 23

Focus- point at which the rock moves. Seismic waves start from focus, where most energy released. Depth of focus controls damage, if focus closer to surface, more damage.

Epicentre- directly above focus on the surface

P waves- faster, shake earth back and forwards, move through solids and liquids.
S waves- slower, moves earth sideways, cannot move through liquids
Surface waves(L waves)- travel nearer to surface, even slower, more destructive

Question 24

What are the effects of an earthquake(primary and secondary?

Answer 24

Primary effect- occur instantly. GROUND SHAKING- how strongly ground shakes depends on how deep the focus is. Type of rock, softer rock like clay will shake easily.

Secondary effects- consequence of something happening. TSUNAMIS- created by undersea earthquakes, when ground jolts under sea, it propels water to make wave. LANDSLIDES- slope on mountains become weaker because of shaking.

Question 25

How to measure an earth quake?

Answer 25

RICHTER SCALE- measure magnitude of an earthquake using seismograph. On the scale numbers are expressed as whole numbers and decimals. No upper limit but largest recorded in Chile 1960- 9.5. Logarithmic scale so a size 6 is 10x larger than a 5 and 100x larger than 4.

MERCALLI SCALE- measures intensity of the impacts of the earthquake. Based on perception of effects on humans, buildings and the environment

Question 26

Define mitigation

Answer 26

reducing damage/severity caused by tectonic plates

Question 27

How to predict an earthquake

Answer 27

• Tilt-meter- check movement in rocks
• Water levels rise in lakes and wells because of cracks in rocks
• Fore shocks before earthquake detected in seisometer
• Animals act strangely before earthquakes
• Seismic history
• Earthquakes mostly happen on plate boundaries, countries informed

Question 28

Describe the features of an earthquake proof building

Answer 28

• Strengthened steel and reinforced concrete supports
• Rubber shock absorbers to absorb energy
• Foundations are deep
• Cross-bracing to give strength and prevent twisting
• Automatic window shutters to prevent falling glass
• Sheer iron core of reinforced concrete and tensioned cables around lift shaft
• Automatic sprinklers

Question 29

Define the global circulation system

Answer 29

The movement of air around the world hemispheres to transport heat from tropical to polar regions

Question 30

What is a composite volcanoes?

Answer 30

Are found at destructive plate boundaries where plates moving towards one another. Magma is viscous and sticky, it moves more slowly and can lead to explosive eruptions.

Question 31

What is a shield volcano?

Answer 31

Are found at constructive plate boundaries where plates move away from each other this allows hot liquid magma from mantle to flow up. Magma spreads out from cones or through fissures. Builds a gentle slope where new oceanic plate being formed.

Question 32

What is a fissure volcano?

Answer 32

At constructive volcanoes where plates separate to leave a rift or fissure.Eruption does not flow from a cone but lava flow out along a fault line and builds up eg. mid Atlantic ridge

Question 33

Caldera volcano

Answer 33

Occurs when a volcano erupts so explosively that the magma chamber empties and the crater collapses into itself.

Question 34

What is a hotspot?

Answer 34

Most volcanoes happen on plate boundaries except for hotspots which occur when an oceanic plate is moving over a hot area of the mantle which creates magma to rise up towards crust . This will punch through the plate and leads to volcanic islands appearing.

Question 35

How to measure a volcano?

Answer 35

Severity of an eruption can be measured on the volcanic explosivity index (VEI). The scale goes from 0-8 and looks at how far the ash plume travelled. the volume of the material ejected and how often that type f eruption occurs. Has a 10 fold increase.

Question 36

Tephra

Answer 36

fine volcanic dust which tends to deposit near the volcano

Question 37

What is the ITCZ?

Answer 37

The inter tropical convergence zone is a low pressure belt which encircles around the equator. Its is where trade winds meet from north and south. The ITCZ tends to migrate from the tropics of cancer of Capricorn.

Question 38

What are the causes, impacts and responses of the earthquake in Nepal?

Answer 38

Location of earthquake- Nepal is between India and china, the earthquake happened in SE of Nepal and SW from mount Everest, affects the capital, the epicentre close to Pokhara and Kathmandu tide in the middle of Nepal, measured 7.9 on Richter scale.

Causes- The Indian plate going north and Eurasian plate moving towards each other, collision plate margin., the plates being forced together 2 cm a year. Plates push together and the material between them is caused to buckle and rise to form mountains and severe earthquakes. Had a shallow focus-15km below surface so damage at epicentre was severe. Gorkha was most impacted, Nepal was LIDC so not prepared,

Impacts- PRIMARY- wrecked houses, destroyed century old building, 11,330 confirmed dead, people buried under buildings, Dharaha tower collapsed, century old building eg. Kathmandu Durbar square and Pata durbar square collapsed. SECONDARY- triggered many avalanches in mount Everest, many tourists, guides being trapped under snow or building, affected economy which was heavily dependant on tourism, trekking and mountain climbing, earthquake felt in Delhi, aftershocks hours later, hundreds of thousands homelessness, airport closed so aid cant be reached 66 magnitude aftershock on 26th april.

RESPONSES- In GORKHA communities build a trail which connects 2 villages, a health care centre and a market. In KATHMANDU Oxfam set up a women’s centre to provide counselling for vulnerable women who were affected in the disaster. International aid from China. DHADING communities pay to build pipelines to get clean water. MADANPUR distribution of winter and shelter kits,tents were placed.