topic 2:weather hazards and climate change Flashcards
what are the three circulation cells and their latitude?
1) Hadley cell- equator to 30 degrees north/south
2) Ferrel cell- 30 degrees north/south to 60 degrees north/south
3) Polar cell- 60 degrees north/south to 90 degrees north/south
what happens at the Hadley cells?
- At the equator warm air rises to 15km, causing low pressure
- This air current divides, cools and moves north and south to from the Hadley cells
- The cooled air sinks at 30 degrees north and south of the equator, leading to high pressure
what happens in the Ferrel cells?
- Some of the cooled air moves back towards the equator as trade winds
- the rest moves to the poles, forming the lower part of the Ferrel cell
what happens in the polar cells?
- at 60 degrees north/south, the warmer air of the Ferrel cells meets the colder polar air.
- The warmer air rises to form the polar cells
- this air travels to the poles, where it cools and sinks, forming areas of high pressure
where does oceanic circulation carry heat to and from?
it carries heat from warmer to colder areas (from the equator to the poles)
how does oceanic circulation move water?
- in the poles water gets very cold and dense so it sinks
- this surface water is replaced by hot water from the equator
what is a glacial period?
a period of colder climate
what is an inter glacial period?
a period of warmer climate
what is the name for the current time period we are living in now?
the Quaternary period
how do Milankovitch cycles cause climate change?
- Milankovitch cycles cause climate change
- these are long term changes to the Earths orbit and position, changing how much solar radiation we receive
how does volcanic eruptions cause climate change?
- in a volcanic eruption dust and ash is ejected into the air
- this acts as a blanket which blocks solar radiation
how does solar radiation cause climate change?
-solar radiation varies causing the Earths temperature to vary
name three causes of climate change?
1) Milancovitch cycles- when the earth gets pulled out of regular orbit
2) solar radiation-radiation levels from the sun varys
3) volcanic eruptions-volcanic ash can deflect sun light away
4) asteroid theory-asteroids can cause dust which blocks radiation
what is evidence for climate change?
1) historical sources- eg diaries
2) ice cores- they trap volcanic ash, microbes and air bubbles that can be used to determine the climate at the time
3) preserved pollen- provides evidence on warm and cold growing conditions
4) tree rings- you can see climate change inside trees as they make yearly growth rings
what is the enhanced greenhouse effect?
when human gas emissions (C02) cause more hot air to get trapped around the Earth causing an increased greenhouse effect
how does the earth receive heat from the sun?
1) Heat energy from the sun passes through the atmosphere and heats up the Earth
2) Much of this energy is radiated back to space
3) greenhouse gases trap some of the heat as it is deflected back as long wavelength radiation
name 4 human causes of climate change?
1) industry- more demand for goods
2) energy- new technology increases demand for electricity
3) farming- population growth causes more demand for food
4) transport- use of cars releases C02
what are the negative impacts of climate change on the environment?
- melting ice sheets causes rise in sea level
- rising sea level may cause soil to get salty and infertile
what are the negative impacts of climate change on people?
- longer periods of drought around the equator so less crops grow
- low lying islands like the Maldives may flood
- photosynthesis at different rates effects food security
what is the medieval warm period?
- a period of warmer temperature in the UK (950-1100)
- because of increased solar radiation, lack of volcanic eruptions and orbital changes
what happened during the medieval warm period?
- more crops
- growing population
what is the little ice age?
- a period of colder temperature in the UK (1600-1685)
- this happened because of increased volcanic activity
what happened in the little ice age?
-the Thames froze
what is the maritime impact on the UK’s climate?
the air reaching Britain contains lots of moisture due t Britain being surrounded by sea
what is the prevailing winds impact on the UK’s climate?
this wind comes from the south west bringing moisture
what is the north Atlantic drifts impact on the UK’s climate?
this ocean current brings warm water north to the UK
what is the atmospheric circulations impact on the UK’s climate?
due to the UK being between the Ferrel and polar cell we get unsettled weather
what is the altitudes impact on the UK’s climate?
the higher the altitude the colder the weather so areas in the UK vary
how do tropical cyclones form?
1) water evaporates from the ocean surface and comes into contact with cold air
2) a column of low pressure develops at the center winds form around the column
3) as pressure in the eye weakens wind speed increases
what are the characteristics of a tropical cyclone?
- low pressure
- rising spiraling air around the eye
- cloud banks called the eye wall surround it
when are tropical cyclones likely to form? northern/southern tropics
northern tropics: june-november
southern tropics:november-april
what is the cyclones track and movement determined by?
cyclone movement:
- prevailing winds
- ocean currents
- can be foretasted using satellite images
cyclone track:
- how far it travels over the ocean
- can travel 600 km a day at 40km/h
what are the hazards of tropical cyclones?
- storm surges: a large mass of water can hit land
- landslides: intense rainfall causes heavy soil which slides down
- coastal flooding: damage to property
- intense rainfall: can cause flooding
- high winds: uproot trees and buildings
what is the scale that categorizes tropical cyclones?
the saffir-simpson scale
what are the categories in the saffri-simpson scale?
numbers 1 being the least damage 5 being the most
Hurricane sandy key facts
1)traveled over the carrabean sea affecting Jamaica, Cuba and Haiti
2)It reached new jersey on the 29 of October 2012
3)wind speeds of 129km/h
most damage on the east coasts states
hurricane sandy social impacts?
- at least 150 deaths
- many areas had no electricity
- homes and businesses damaged
- schools closed for days
hurricane sandy economic impacts?
-estimated property damage of 65 billion dollars
hurricane sandy environmental impacts?
- damage to nature reserves
- raw sewage leakage into water supplies
what responses where there to hurricane sandy?
- charity concerts
- new government office to support rebuilding
- American Red Cross helped provide relief to victims
what are the key facts from typhoon Haiyan?
1) formed in the south pacific ocean
2) wind speeds of 300km/h when it reached land
3) most damage on islands Samar and Leyte
4) flooding and landslides in the Philippines
hurricane Haiyan social impacts?
- 6,000 deaths
- 600,000 people displaced from homes
- many homes destroyed
hurricane Haiyan economic impacts?
- estimated damage of 2 billion dollars
- damaged infrastructure made it hard for aid to be transported
hurricane Haiyan environmental impacts?
- trees uprooted
- oil spills
what was the response to typhoon Haiyan?
- people donated money
- loans from countries to the Philippines from countries like the UK
- world health organization helped the Philippines get healthcare
what are arid areas?
areas that are normally dry
what is drought?
a time when an area gets an unexpected lack of water
what are key factors of a arid environment?
- permanent low precipitation
- 10-250mm of precipitation per year
- high pressure conditions (no clouds)
- in the tropics
- places of high pressure
what are key factors of drought conditions?
- temporary low precipitation
- high pressure conditions (no cloud)
- can happen anywhere
what is a meteorological cause of drought?
- less than average precipitation causing drought
- in the UK this means high pressure which blocks the low pressure
what is a hydrological cause of drought?
- when rivers/lakes receive less precipitation
- this has a knock on effect with the surrounding area
what effects does circulation cells have on drought?
- where the Hadley and Ferrel cells are descending dry air causes little precipitation
- rainfall happens in wet seasons and if it doesn’t come, the area has drought
how can humans cause drought?
- deforestation as trees remove CO2 and put water vapor in the air from the ground
- dams can cause drought as downstream places would get less water
- agriculture as MCH4 is released from cows and water is used in agriculture
what caused drought in California, USA?
lower rainfall and snow levels
what where the main hazards of the drought in California?
- subsidence as ground water levels dropped causing land to settle at a lower level
- contamination of land and drinking water by seawater, draw inland by a lack of pressure
- wildfires which started and spread quickly as vegetation was so dry
- rivers have dried up
what are the impacts on people and ecosystems in California?
- central valley is worst effected area
- costing California $2.7 billion a year
- 542,000 acres taken out of crop production
- wildfires
how has people responded to the drought in the USA?
- education campaigns
- laws to cut water use
- homeowners encouraged to check water leaks
- farmers encouraged to use water-efficient irrigation
what where the main hazards in the Ethiopian drought?
- reduced crop yields leading to malnutrition
- longer journeys to find water leading to more kids not getting education
- migration to survive
what are the impacts on people from the Ethiopian drought?
- death of livestock causing food crisis
- malnutrition/more vulnerable to disease
- kids have to stay out of school to get water
- loss of crops
what are the impacts on ecosystems from the Ethiopian drought?
- loss of habitat for fish and wildlife
- increased disease in wild animals
- migration of wildlife
- extinction
- loss of 200,000 hectors of forest per year
how have people responded to the Ethiopian drought?
- governments have given aid- USA gave $128.4 million
- Education agency helping people get jobs
- large charitable events- eg Live aid
- Oxfam and UNICEF helping people get water
what is weather?
the day to day conditions of the atmosphere
what is climate?
the average weather conditions
what is the Coriolis effect?
the apparent deflection of winds to the right in the northern hemisphere and to the left in the southern hemisphere due to the earths rotation
how is high pressure caused and what is its effect?
- caused by cold air rising
- causes hot weather
how is low pressure caused and what is its effect?
- caused by air rising
- causes lousy weather
why is the earth warmer around the equator?
because the solar radiation is more concentrated whereas at the poles it is more spread out
what are the lines of latitude on the earth?
arctic circle 66.5 n tropic of cancer 23.5 n equator 0 tropic of Capricorn 23.5 s arctic circle 66.5 s
what is the inter tropical convergence zone? (ITC2)
a belt of low pressure that circles the earth near the equator where trade winds from the southern and northern hemispheres meet
what are jet streams?
narrow bands of strong winds in the upper atmosphere
- polar jet streams are the same but at the polar cells
- subtropical jet streams are the same but in the tropics
what is the UKs climate like?
- temperate climate
- wet winters and warm summers
what is the UK’s climate like in north west Britain?
- mild winter
- cool summers
what is the UK’s climate like in north east Britain?
- cold winters
- warm summers
what is the UK’s climate like in south west Britain?
- mild winters
- warm summers
what is the UK’s climate like in south east Britain?
- cold winters
- mild summers
what conditions do tropical cyclones form in?
- sea temp must be 26 degrees
- high humidity
