geography global hazards Flashcards
(38 cards)
What are the three cells of air
Hadley, Ferrel, Polar
What happens in the hadley cell?
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.
What happens in the ferrel cell?
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.
What happens in the polar cell?
Smallest and weakest cell, air sinks over highest latitudes at poles and flows to the lower latitudes.
What happens in areas of high pressure? Where are they?
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
What happens in areas of low pressure? Where are they?
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.
What are the places of extreme weather(windiest, rainiest, coldest, hottest, driest)
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
Where are droughts mostly found?
located in areas such Africa south america india .
Where are tropical storms mostly found?
Near the equator, 15 degrees N and S, East asia, east pacific 3+ and in Caribbean and madagascar 1-3
What is the recipe for extreme weather?
ocean is 26.5C, Water depth=60+m deep, 5-15 degrees N/S of the equator
Describe how a tropical storm is formed
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
What happens in an normal, el nino and la nina year?
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
What is a drought?
period with lack of precipitation
What is some backgroud info about murray darling basin?
14% of Australia land, 20% less rainfall fallen that long term average, generate 39% of Australia agriculture- grain, fruit and cattle
What are the causes, impacts and responses to the murray darling basin?
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.
Explain the causes, impacts and responses to the flooding in cumbria flooding in 2015?
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
What is a destuctive plate boundary?
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.
What is a conservative plate boundary?
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.
What is a collision plate boundary?
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
What is a constructive plate boundary?
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
What are the layer of the earth? Describe them
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
Describe the convection currents
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.
Describe the cross-section of an earthquake
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
What are the effects of an earthquake(primary and secondary?
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.
