ocr b global hazards

what is the global circulation system?

the global circulation system is the large-scale movements of air over the earths surface. these circulations of air transport heat from the tropical regions at the equator where the earth gets more heat from the sun to the polar regions at the poles

how does the global circulation system work?

the world is divided into two at the equator line to create northern and southern hemispheres and in each hemisphere there are cells called polar ferrel and hadley and within these cells air circulates in the troposphere which is an area of the atmosphere 10-15km high and the tropospere is where the earth's weather takes place. the three cells play an important role in creating distinct climate zones

Hadley Cell

the hadley cell is the largest cell which extends from the equator to approxiamatley 30 degrees north and south

trade winds are winds that blow from the tropical regions towards the equator and they usually travel from an easterly direction. near the equator the trade winds meet and the warm air rises and forms thunderstorms . from the top of these stroms air flows towards higher latitudes where it becomes cooler and it sinks over subtropical regions

Ferrel Cell

this is the middle cell which occurs from the edge of the hadley cell to 60 degrees approxiamatley.

this cell is the most complicated because it moves in the opposite direction from the hadley and polar cells similiar to a cog in a machine. air in this cell joins the sinking air of the hadley cell and it travels at low heights to mid latitudes where it rises along the border with the cold air of the polar cell. this normally occurs around the latitude of the uk and accounts for the frequentley unsettled weather. the air then flows back towards the low latitude, in the direction of the equator

Polar Cell

this the smallest and weakest cell which extends from edge of the ferrel cell to the poles at 90 degrees and the air in this cell sinks over the highest latitudes at the poles and flows towards the lower latitudes

how does pressure infuence the climate?

as we know wind is air moving from high presssure to low pressure the atmospheric air pressure is the force exerted on the earths surface by the weight of the air and it is measured in millibars.the normal range of air air pressure goes from 980 to 1050 millibars . where the air in the hadley cells rises at the equator low pressure is created. however where the hadley and ferrel cells meet at 30 degrees north and south of the equator,air descends which creates a high pressure on the ground below. the contrasts in air pressure associated with different cells results in regions with distinct average temparature and rainfall patterns.

what happens in areas of low pressure ?

a low pressur esystem occurs when the atmospheric pressure is lower than the surrounding area. it is normally associated with high winds and warm rising air. as the warm air cools and condendes it forms clouds as it rises. then the water vapour condenses and turns into a liquid resulting in precipitate falling.however the daytime range of temparatures are unlikley to be large because the cloud cover reflects solar radiation during the day and it traps the heat during the night

what happens in the areas of high pressure ?

as the temparatures cool the air starts to become more dense which results n the cooler air starting to sink andincreases the air pressure. the cool air warms up and causes the clouds to evaporate. also heavy rain at the equator would mean that most of the moisture in the atmosphere would be removed before the air ends up reaching the sub-tropics and at 30 degrees north and south of the equator high pressure systems are commonly associated with clear skies and dry calm weather

how does the global circulation of the atmosphere cause weather extremities in the atmosphere ? temperate zone

60 degrees north and south of the equator two air types meet and one is warm from the ferrel cell and cool from the polar cell . low pressure is then created from the rising of the warm subtropical winds over the cold polar winds at a front and as the air rises and cools it condenses and clouds are then formed ultimatley resulting in rainfall.

how does the global circulation of the atmospher cause weather extremities in the atmosphere- tropical climate

this is a belt of quite low pressure and heavy rainfall and thunderstorms as a result of the rising air in the hadley cel lplaces such as north brazil expierience this climate

how does the global circulation of the atmosphere cause weather extremities in the atmosphere-sub-tropical desert climate

at 30 degrees north and south of the equator there is a high pressure as a result of sinking dry air as the hadley and ferrel cells meet which creates a belt of desert regionswhich inculdes the sahara. the day time temparatures can exceed 40 degrees while at night due to the lack of a cloud cover the temparature can fall to below freezing because the cloud cover is not there to act as a blanket and trap the heat instead of letting it freely escape into space

how does the global circulation of the atmosphere cause weather extremities in the atmosphere-polar

at the highest latitudes the ar is sinking creating an immense amount of pressure which is then characterised by the dry icy swinds caused by the spin of the earth and in some places in antartica the average annual wind speed is 50mph

how is extreme weather associated with wind ?

tropical storms rely greatly on wind speeds because they need to change slowly with height because if the speeds are greater in the upper atmosphere the storms could be sliced in two. inside the eye of the storm the wind speeda are much higher

how is extreme weather associated with temparature ?

temparature affects droughts because as the temparature increases more of the water is needed to grow crops and more water is then lost through evaporation

how are weather extremes associated with precipitation ?

flood rates can be increased by precipitation because there might be so much that the rivers all overflow and because the ground would have already absorbed so much water this mght make the ground impermeable resulting in flooding

How are tropical storms formed?

Tropical storms form between approximately 5° and 30° latitude. Because of easterly winds they initially move westward.

The air above the warm ocean is heated. Once the ocean water reaches at least 27°C, the warm air rises quickly, causing an area of very low pressure.

As the air continues to rise quickly it draws more warm moist air up from above the ocean leading to strong winds.

The rapidly rising warm air spirals upwards, cools, condenses and large cumulonimbus clouds form.

These clouds form the eye wall of the storm and produce heavy rainfall.

In the centre of the storm, cold air sinks forming the eye of the storm - here, conditions are calm and dry.

how does the coriolis effect help with the formation of tropical storms ?

the coriolis effect acts on winds because the earth is spinning altering the paths of the wind making it take more curved paths

what is wind direction like during a normal year ?

udring a normal year the trade wind goes westwards towwards southeast asia and australia and away from south america this then causes water to sink in that direction which causes australia and southeast asia to have high rainfall due to the warm water pooling and evoparation of water evantually condensing into a cloud and precipitating. there is also a low atmospheric pressure because the air rises from the warm water . in south america there is a high atmospheric pressure because the shallow position of the thermocline allows winds to pull up water from below air . the pressure is high because the airdesendes due to the warm and dry conditions

what is the wind direction like during an el nino year ?

during an el nino year the trade winds can get weaker or they can blow eastwards resulting in the sea level to rise near southamerica and warm water to pool up causing a lower pressure and due to the rising warm air there is more rainfall which causes the loss of the cold water pwelling zone and in australia and southease asia the water becomes cooler resulting in more stable dry conditions but there is a possibility of droughts

what is the wind direction like during a la nina year

ecrything is much more extreme but the wind direction is the same as it normally is (going towards south east asia and australia) this results in an excess amount of warm water pooling resultant in flooding due to excess rainfall and causes low atmospheric pressure since air rises and can droughts in south america because of the cold water upwelling zone causing a high atmos pressure causing air sinking and more droughts

what were the causes of the drought in australia ?

. when el nino is present australia becomes much more drier and than normal and the chances of rainfall decrease because during el nino the trade winds over the pacific ocean that normally bring warm weaken which causes the water to cool and the rainfall to diminiah which causes eastern australia to heat up and get drier

additionally australia has a population of 23 million people and australia cannot maintain the current population growth in relation to access to water because of the droughts causing a decreases in water resources hence making the country overpopulated

eaatern australia is also home to the murray darling river basin which is incredibly large as big as france and spain combined however it is home to 2 milion people and it is under alot of pressure to provide the water needed for australias agricultural produce. the water resources are being over-allocated and too much of the water has been extracted further more the mean daily temparatures have also been above average by 0.8 celsius and 94 percent of the rainfall gets evaporated by this

the social consequences drought in australia ?

people who live in rural areas were migrating due to the lack of water which put a greater pressure on the population of the cities. the rural suicide rates also soared because of the high amount of stress put on the people

what were the economic consequences of the drought in australia ?

the farmers were forced to sell the cattle because because they didnt have enough resources to feed them. the food prices also soared because there wasnt enough water to sustain normal crop growth so as a result of this australia became more reliant on imported food

due to lacking water resources the water bills ros 20 percent in 2008 tourism was also negativley affected because of the publics negative views about drought. agricultural production was also severley affected by this furthermore because of how reliant cotton is on water and how much water it actually consumes almost 10,000 people directly employed by the cotton growing industry were affected. the number of dairy farms also were reduced more than half because of how much water they consume

what were the enviromental consequences of the drought in australia ?

there was a huge loss of vegitation and wildlife due to not enought water resources to supply water to them. soil erosion is also increased because as the soil dries out it becomes looser and it can be easily blown away. further more the grassland has also turned into scrubland because they occupy the driest of areas and as the amount of rainfall decreases the plants grow further and further apart until the land is refferred to as a dessert. the energy from hydroelectric power was also reduced( energy created from motion of water) resulting in an increased use of fossil fuels and more pollution. the quality of water was reduced because of increased amount of algeo growth due to the high amount of sunlight and lo wamount of water increasing the growth of it

what were the responses to the australia droughts

waste water from showers baths washbasins and more and being recyled into water used for irrigation or toilet flushing.rainwater storage tanks were also provided so that in the future people had a source of water during drought.by using . more efficient irrigation systems were also introduced such as drip irrigation which filters water down into the soil and into the root system so that some of the water percolates into the groundwater system so it can be used again for irrigation in the future.some actions were restricted or prohibited due to water restrictions such as watering lawns and washing wehicles also refilling swimming pools which could further reduce tourism if waterparks arent supplied with a appropriate amount of water as they are normally tourist attractions.

the human causes of flooding in cumbria-

there was a decreased amount of vegitation to intercept rainfall because of deforestation

impearmeable surfaces such as concrete can cause floods because the water cant be absorbed and this is mostly found in urban areas

there was a lack of flood defences such as dams which would confine and control the amount of water reducing the chance of the water going on the land.

the river channel is also blocked by rbbish and pollution resulting in backflow of water which reduces the flow capacity and raises he water levels

the rivers hadnt been dredged which is the digging up of sediment and this would have prevented shallow river so it might have been able to hold more water

natural and physical causes of cumbrian flooding

there was a high amount of rainfall which exceeded 300 mm which could have been caused by its location ina mild,moist south westerley airstream bringing prolonged and heavy rainfall . hills are close by causig surface run off. steep slopes as a result of gravity would result in water flowing down much more quickly.there is an increased amount of flood plains so this would mean that the water can spread out very easily. The number of tributaries flowing into a river affects the likelihood of floods. If a river has a lot of tributaries, the river's discharge will be much higher because lots of water will be entering it from its tributaries.

what is uk relief rainfall ?

uk relief rainfall happened with cumbria because the land is higher on the west and it is lower on the east so warm westerly winds carry moisture from the atlantic ocean went over the hill and started to precipitate

short term responses of cumbrian flooding

rnli volunteers evacuated 200 people 350 soldiers were made availible to assist with the flooding response

army trucks were used as ambulances to ferry patients to the hospital

long term responses of cumbrian flooding

old bidges were replaced with sing span bridges to enable more water to flow underneath reducing the amount of blockages and upstream flooding.

they removed build up of gravel from the derwent in workington and cockermouth

investigating the use of redundant birds park reservoir it can hold the excess flood water until the water on the surface runs away and after the heavy rainfall sops and there are no more flood risks the water is released

describe the structure of the earth and how this explains the proccess of plate tectonics

the earth is made of the crsut also known as the lithosphere the mantle which has magma the inner core and the outer core. the core is extremley hot and heat is radiated from it to heat up the mantle which it creates the molten magma. the hot magma churns around in the mantle via a process called convection as the magma churns it gets hotter and decreases in density so it rises towards the crust and it cools and becomes more dense and sinks back down again. these convection currents are what results in the movement of tectonic plates as a result of friction applied onto the plates by the magma

oceanic and continental plate boundaries

oceanic crust is found underneath the ocean and it is 5-10 kilometres thick. continental crust is found beneath the land and it is between 25 to 100km thick

What is a plate boundary?

a plate boundary is where two or more plates meet and different hazards and landforms can be found at each plate boundary some boundaries move away from eachother such as destructive and collision and some towards eachother such as constructive and some slide past eachother such as conservative

what happens at a destructive boundary also known as convergent

when a heavier oceanic plate meets a lighter oceanic plate it is forced to subduct into the mantle which causes friction because the plates rub and it leades to melting and the production of volcanic ridges. two of the plates push together and land can get destroyed because of this. as the denser plate sinks into the mantle it can rub and cause friction which melts the plate and creates magma this can lead to volcanic eruptions as the magma can end up reaching the surface as lava. earthquakes can also occur due to the stress from the friction of the plates

what happens at the collision zone also known as convergent destructive boundary

if two continental plates collide neither one will subduct because they are both the same density and instead the plates push together and are forced upwards creating fold mountains such as the himilayas. as the collision causes land to squeeze upwards and fold mountains to form as the ground buckles and reshapes under pressure severe earthquakes can occur in the proccess

what happens at a constructive divergent boundary

when two tectonic plates are pulled in opposite directions this divergence allows magma from the mantle to reach the earths surface through spreading volcanic ridges. as the plates move apart magma from the mantle can reach the surface and erupt through pissures and faults causing volcanoes and creating new land as the lava emerges and spreads out

what happens at a conservative transform boundary

if two plates slip past eachother they will snag and build up pressure until they finnally jolt past eachother creating earthquakes and rifts in the earths surface. as the plates move past eachother their rough edges snag and stick like velcro which can cause friction and stress to build up until one plate snaps and jolts forwardswhich causes violent earthquakes

Hotspots

Hotspots are places where the magma rises up through the crust. They are caused by a static source of magma, often away from plate margins. As the plate moves away from the hotspot, a new volcano island will form.

how does the movement of plate cause earthquakes

tectonic plates are not smooth they are jagged and rocky and theit edges grind together and stick like velcro. this snagging creates immense pressure which means that the friction will build up until it reaches a point in which the rocks can no longer cope with the stress and at this point the rocks suddenley jolt and move forwards resulting in the release of energy through seismic waves which radiate out like shockwaves through the rock

What is the focus?

the focus is the point which the ground snaps and it can be at different depths within the plate. if the focus is shallow this means that it happened close to the surface increasing damadges a deep focus may cause less damadge because the energy has to travel further before being released

what is the epicentre

the place where the earthquake is felt the strongest most likley its above the focus

how does plate movement cause a composite volcano?

composite volcanoes are found at destructive plate boundaries where the plates are moving towards one another the magma is much more sticky and viscous than when it is found at constructive plate boundaries so it moves more slowly and it can lead to more explosive eruptions steeper sided volcanoes are built up in layers every time a eruption occurs and it is steeper and made of layers of lava and ash

shield vlocanoes plate movemnt

shield volcanoes are found at constructive plate boundaries where the plates are moving away fromeach other allowing hot liquid magma from the mantle to flow up and to be erupted to the surface often the magma erupted at a constructive boundary is more fluid that the other boundaries and it spreads out the cone or through the fissures which builds a gentle volcano shape

what were the causes of the earthquake in nepal

nepal sits on the boundary between the eurasian and indo ausralian plates being forced together at approxiametley 2cm per year this creates pressure so the rocks begun to crumple and form mountains like the himilayas

the focus was 15km below the surface which is bvery shallow so the shaking is worse and the crust moved 3m in some places and the earth quake measured a 7.9 on the richter scale

social impacts of nepal earthquake

resulted in mass migration from impacted areas for a short while

more than 9000 people were killed

12000 injured

triggered avalanches at the himilayas affecting climbers

most peoples house were buried by landslides or damadged by shaking half village population missing or dead hundreds of thousands made homeless ad nepal is a cold country

airports were temporarily shut

enviromental impacts of nepal earthquake

avalanches triggered at the himilayas

most houses buried by landslide villages buried

economic impacts of nepal earthquake

9000 dead 12000 injured

several ancient buildings were knocked down

ancient temple collapsed in tourist location in kathmandu and the economy of nepal is heavily dependent on tourism

airport temporary closure

lost over 1/30th of gdp in the year of the earthquake

over 100,000 made homeless

how to predict earthquake

radon gas emission-radioactive isotope released by seismic stress before the rock fractures

electromagnetism-passing electromagnetic shocks or waves through rocks to detect fractures begining to develop

historic trends-looking at history of past events which might identify timescales

trade winds

trade winds are winds that blow from east to west to just about north and south of the equator

how does the continentality affect the climate of a location

The sea affects the climate of a place. Coastal areas are cooler and wetter than inland areas. Clouds form when warm air from inland areas meets cool air from the sea. The centre of continents are subject to a large range of temperatures. In the summer, temperatures can be very hot and dry as moisture from the sea evaporates before it reaches the centre of the land mass.

How does ocean currents affect climate?

Ocean currents can increase or reduce temperatures. The diagram below shows the ocean currents of the world . The main ocean current that affects the UK is the Gulf Stream.

The Gulf Stream is a warm ocean current in the North Atlantic flowing from the Gulf of Mexico, northeast along the U.S coast, and from there to the British Isles.

The Gulf of Mexico has higher air temperatures than Britain as it is closer to the equator. This means that the air coming from the Gulf of Mexico to Britain is also warm. However, the air is also quite moist as it travels over the Atlantic ocean. This is one reason why Britain often receives wet weather.

The Gulf Stream keeps the west coast of Europe free from ice in the winter and, in the summer, warmer than other places of a similar latitude.

how do directions of prevailing winds affect the climate

Winds that blow from the sea often bring rain to the coast and dry weather to inland areas. Winds that blow to Britain from warm inland areas such as Africa will be warm and dry. Winds that blow to Britain from inland areas such as central Europe will be cold and dry in winter. Britain's prevailing (i.e. most frequently experienced) winds come from a south westerly direction over the Atlantic. These winds are cool in the summer, mild in the winter and tend to bring wet weather.

how does teh relief of land affect the climate

Climate can be affected by mountains. Mountains receive more rainfall than low lying areas because as air is forced over the higher ground it cools, causing moist air to condense and fall out as rainfall.

The higher the place is above sea level the colder it will be. This happens because as altitude increases, air becomes thinner and is less able to absorb and retain heat. That is why you may see snow on the top of mountains all year round.

how does distance from the equator affect climate

The distance from the equator affects the climate of a place. At the poles, energy from the sun reaches the Earth's surface at lower angles and passes through a thicker layer of atmosphere than at the equator. This means the climate is cooler further from the Equator. The poles also experience the greatest difference between summer and winter day lengths: in the summer there is a period when the sun does not set at the poles; conversely the poles also experience a period of total darkness during winter. In contrast, day length varies little at the equator.

ho does altitude affect climate

High-altitude locations are usually much colder than areas closer to sea level. This is due to the low air pressure

How does latitude affect climate?

The closer you are to the equator, the hotter the climate

What is the thermocline?

is the transition layer between the warmer mixed water at the surface and the cooler deep water below. It is relatively easy to tell when you have reached the thermocline in a body of water because there is a sudden change in temperature.

where are tropical storms found ?

over tropical and sub tropical waters between 5 and 30 degrees north and south of the equator

where the temparature of the surface layer of ocean water is in excess of 26.5 degrees and at a depth of atleast 50 to 60m

at least 500 km away from the equator which is where the corliolis effect is strong enough to make the weather system spin

conditions needed for tropical storms

High sea temperatures of at least 27°C.

Converging winds near the ocean surface forcing air to rise and form storm clouds.

Winds that do not vary greatly with height - known as low wind shear. ...

Sufficient distance from the equator for a spin such as the Coriolis force to take effect.

Human causes of drought

Agriculture - using large amounts of water to irrigate crops removes water from lakes, rivers and groundwater. Some crops require more water than others, eg cotton.

Dam building - large dams can be built across a river to produce electricity and store water in a reservoir. This can reduce river water flowing downstream and cause drought below the dam.

Deforestation - removing trees can reduce the amount of water stored in the soil as rain tends to fall and wash off the land as surface run-off. This leaves the ground vulnerable to erosion and desertification which can lead to drought.

Climate change - it is predicted that climate change will cause some places around the world to get hotter, which will increase evaporation and some areas to receive less rainfall - both increasing the risk of drought.

physical causes of drought

Droughts occur when there is abnormally low rainfall for an extended period of time. This means that a desert would not be considered in drought unless it had less rainfall than normal, for a long period of time. Droughts can last from weeks to months and even years.

What is the athenosphere?

The asthenosphere is a layer (zone) of Earth's mantle lying beneath the lithosphere. It is a layer of solid rock that has so much pressure and heat the rocks can flow like a liquid.

what is the difference between primary and secondary effects ?

Primary effects are things that happen immediately as a result of a hazard. Secondary effects are things that happen because of something else happening

what is the difference between the richter and mercalli scale

While the Mercalli scale describes the intensity of an earthquake based on its observed effects, the Richter scale describes the earthquake's magnitude by measuring the seismic waves that cause the earthquake.

richter scale based on seisometer mercallli scale based on perception of the effect

What is a seisometer?

Seismometers allow us to detect and measure earthquakes by converting vibrations due to seismic waves into electrical signals, which we can then display as seismograms on a computer screen. Seismologists study earthquakes and can use this data to determine where and how big a particular earthquake is.

What is a seismograph?

A seismogram is a record of the ground motions caused by seismic waves from an earthquake. A seismograph or seismometer is the measuring instrument that creates the seismogram.

how c an a building be modified to make it more earthquake proof ?

rubber shock absorbers in the foundations to absorb the Earth tremors

steel frames that can sway during Earth movements

open areas outside of the buildings where people can assemble during an evacuation

low-cost methods such as wire mesh retrofitting are used in rural areas and low income countries (LICS) - these are affordable and appropriate to the resources and people living there

Lightweight roofs designed to reduce damage and injury

Responses to the Nepal Earthquake

kits were given to 25,000 families with 5 people per household with ropes,solar panels,cooking gear. most peoplerecieved them but it was over a nine month period

cash for work schemes were proposed so that people could reconstruct paths to other villages and this includes access to markets and health services.

cash for work scheme proposed so that a new rice field irrigation system could be dug out and to rebuild a water source so they have food.