date: 1-jan-14 as unit 1 topic 1 el niño/la niña- el niño/la niña- short term climatic change
TRANSCRIPT
Date: 10 Apr 2023 AS Unit 1 Topic 1
El NiEl Niñño/La Nio/La Niñña-a-Short term climatic Short term climatic
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Date: 10 Apr 2023 AS Unit 1 Topic 1
http://www.bbc.co.uk/weather/features/el_nino_events.shtml
http://www.pbs.org/wgbh/nova/elnino/
http://oceanworld.tamu.edu/
El Nino/La Nina: A WELCOME or UNWELCOME VISITOR?
• P 24-25 PearsonP 24-25 Pearson• P 19-20 Philip AllanP 19-20 Philip Allan• 2 x Geofiles (on the blog)2 x Geofiles (on the blog)
Date: 10 Apr 2023 AS Unit 1 Topic 1
• El Nino and La Nina are amongst the most El Nino and La Nina are amongst the most powerful phenomena on the earth as they powerful phenomena on the earth as they affect the climate over almost half of the affect the climate over almost half of the earth.earth.
• El Nino (means male child in Spanish) and El Nino (means male child in Spanish) and it refers to a weak warm current appearing it refers to a weak warm current appearing around Christmas along the coast of around Christmas along the coast of Ecuador and Peru. They happen every 3-4 Ecuador and Peru. They happen every 3-4 years and may last from 12-18 months.years and may last from 12-18 months.
• Over the last few decades there have been Over the last few decades there have been more stronger events and the term El Nino more stronger events and the term El Nino is now linked more closely to these.is now linked more closely to these.
Date: 10 Apr 2023 AS Unit 1 Topic 1
• La Nina (meaning female child in La Nina (meaning female child in Spanish) refers to an anomaly of cold Spanish) refers to an anomaly of cold sea surface temperatures found in the sea surface temperatures found in the eastern tropical Pacific (by Australia eastern tropical Pacific (by Australia and Indonesia etc)and Indonesia etc)
• La Nina episodes may follow El Nino La Nina episodes may follow El Nino (but not always. (but not always.
Date: 10 Apr 2023 AS Unit 1 Topic 1
What is happening usually?What is happening usually?
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Hadley Cells
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Normal yearsNormal years
•
Date: 10 Apr 2023 AS Unit 1 Topic 1
• Under normal conditions there is high air Under normal conditions there is high air pressure off the coast of Peru and pressure off the coast of Peru and Ecuador with descending air resulting in Ecuador with descending air resulting in the Atacama desertthe Atacama desert
• And there is low air pressure over the And there is low air pressure over the western Pacific (Australia and Indonesia) western Pacific (Australia and Indonesia) giving heavy convectional rainfall.giving heavy convectional rainfall.
• This movement of air results in the This movement of air results in the Walker cell.Walker cell.
• The upper air moved west to east and The upper air moved west to east and the lower air moves from east to west as the lower air moves from east to west as the the trade windstrade winds..
Date: 10 Apr 2023 AS Unit 1 Topic 1
• Surface water gets pushed westwards Surface water gets pushed westwards …. The sea level is normally 60cm …. The sea level is normally 60cm higher in the Philippines than in higher in the Philippines than in Panama/ColombiaPanama/Colombia
• Water flowing westwards stays warm Water flowing westwards stays warm (28 degrees C in the western Pacific).(28 degrees C in the western Pacific).
• Cold water(20 degrees C) that wells up Cold water(20 degrees C) that wells up near Peru and Ecuador is rich in near Peru and Ecuador is rich in plankton and great for fishing. plankton and great for fishing.
Date: 10 Apr 2023 AS Unit 1 Topic 1
And in El Nino years? And in El Nino years?
• These are scientifically called an El Nino These are scientifically called an El Nino Southern Oscillation (ENSO) and happen Southern Oscillation (ENSO) and happen every 3-4 years and may last from 12-every 3-4 years and may last from 12-18 months.18 months.
• There is a reversal to normal conditions.There is a reversal to normal conditions.• Pressure rises over the Western Pacific Pressure rises over the Western Pacific
(Indonesia and Australia) and falls over (Indonesia and Australia) and falls over the Eastern Pacific (Peru and Ecuador)the Eastern Pacific (Peru and Ecuador)
Date: 10 Apr 2023 AS Unit 1 Topic 1
• The Inter Tropical Convergence Zone (ITCZ) The Inter Tropical Convergence Zone (ITCZ) shifts South and causes trade winds to weaken shifts South and causes trade winds to weaken and maybe even reverse their direction.and maybe even reverse their direction.
• Air descends over South East Asia (drier Air descends over South East Asia (drier weather) and ascends over the west coast of weather) and ascends over the west coast of South America (wetter weather).South America (wetter weather).
• The changing trade winds means that sea level The changing trade winds means that sea level in South East Asia tends to fall and it rises in in South East Asia tends to fall and it rises in tropical South America. tropical South America.
• Surface temperatures to the East is warmer and Surface temperatures to the East is warmer and there is less upwelling of cold water off Peru. there is less upwelling of cold water off Peru. Sea temperatures there may rise by 6 degrees C Sea temperatures there may rise by 6 degrees C so plankton suffers as does Peru’s fishing so plankton suffers as does Peru’s fishing industry. industry.
Date: 10 Apr 2023 AS Unit 1 Topic 1
El Nino
Normal Year
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Sea Level
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El Niño Builds, Warm Wave Surges Toward South America November 20, 2006
Date: 10 Apr 2023 AS Unit 1 Topic 1
• Examples of El Nino – 1982-83, 1986, Examples of El Nino – 1982-83, 1986, 1992-93, 1997-981992-93, 1997-98
• Effects of El NinoEffects of El Nino• Change of weather around the worldChange of weather around the world
• The very strong El Niño of 1997-98 caused:The very strong El Niño of 1997-98 caused:
• South AmericaSouth America
• High evaporation and precipitation – For each of 12 days in early March Peru High evaporation and precipitation – For each of 12 days in early March Peru got 6 months of normal rain. Flash floods killed 292, injured more than 16,000, got 6 months of normal rain. Flash floods killed 292, injured more than 16,000, destroyed 13200 homes and wrecked roads and farmland. Half a million destroyed 13200 homes and wrecked roads and farmland. Half a million Peruvians affected. Peruvians affected.
• Economic disaster to the Peruvian fisheries.Economic disaster to the Peruvian fisheries.
• Some plants blooms for the first time in 100 years in the Atacama desertSome plants blooms for the first time in 100 years in the Atacama desert
• Indonesia and AustraliaIndonesia and Australia
• Droughts in Australia, which caused a water shortage.Droughts in Australia, which caused a water shortage.
• Lake Eyre in Australia dried upLake Eyre in Australia dried up
• Indonesian forest fires caused severe haze over several countriesIndonesian forest fires caused severe haze over several countries
Date: 10 Apr 2023 AS Unit 1 Topic 1
Effects of El Nino in other Effects of El Nino in other parts of the worldparts of the world
• Other parts of the worldOther parts of the world
• severe coastal storms, heavy rainfall, flooding and mud slides in California severe coastal storms, heavy rainfall, flooding and mud slides in California on the west coast of the United States.on the west coast of the United States.
• droughts in Mexico and Central America, which led to forest fires that droughts in Mexico and Central America, which led to forest fires that burned for long periods of time and sent heavy smoke north to the United burned for long periods of time and sent heavy smoke north to the United StatesStates
• unusually mild winters on the east coast of the United States – very little unusually mild winters on the east coast of the United States – very little snow in the Rockiessnow in the Rockies
• Heavy rain increases wildlife in BotswanaHeavy rain increases wildlife in Botswana
• Late arrival of monsoon in Indian subcontinentLate arrival of monsoon in Indian subcontinent
• Droughts in SE AsiaDroughts in SE Asia
Date: 10 Apr 2023 AS Unit 1 Topic 1
http://www.dailytelegraph.com.au/news/gallery/gallery-e6frewxi-1225778417848?page=7
Sydney Dust Storms Sept 2009
Date: 10 Apr 2023 AS Unit 1 Topic 1
La NinaLa Nina
• The ‘little girl’ is the reverse of El Nino. The ‘little girl’ is the reverse of El Nino. • It has occurred less frequently than El It has occurred less frequently than El
Nino.Nino.• It is less easy to predict due to less It is less easy to predict due to less
evidence.evidence.• The low pressure over the Western Pacific The low pressure over the Western Pacific
(Indonesia and Australia) becomes even (Indonesia and Australia) becomes even lower and the high pressure over the lower and the high pressure over the Eastern Pacific (Peru and Ecuador) even Eastern Pacific (Peru and Ecuador) even higher. higher.
Date: 10 Apr 2023 AS Unit 1 Topic 1
Date: 10 Apr 2023 AS Unit 1 Topic 1
Date: 10 Apr 2023 AS Unit 1 Topic 1
• Rainfall increases over South East AsiaRainfall increases over South East Asia• And drought conditions happen in South And drought conditions happen in South
America.America.• The increased difference in air pressure The increased difference in air pressure
over the Pacific strengthens trade over the Pacific strengthens trade winds.winds.
• Larger amounts of water are sent Larger amounts of water are sent westwards giving higher sea levels in westwards giving higher sea levels in IndonesiaIndonesia
• There is an even greater upwelling of There is an even greater upwelling of cold currents on the Peruvian coastcold currents on the Peruvian coast
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One of the strongest La Niñas blankets the Pacific Ocean near the equator,
This La Niña is indicated by the blue area in the centre of the image along the equator. Blue indicates lower than normal sea level (cold water). The data were gathered in early April 2008
Date: 10 Apr 2023 AS Unit 1 Topic 1
Effects of La NinaEffects of La Nina
• Scientists believe that la Nina could be Scientists believe that la Nina could be linked to greater hurricane activity in linked to greater hurricane activity in the Caribbean.the Caribbean.
• It also interrupts the jet stream by the It also interrupts the jet stream by the mid latitudes, like the UK, giving mid latitudes, like the UK, giving stormier, wetter and cooler conditions.stormier, wetter and cooler conditions.
• See the diagram on the next page. See the diagram on the next page.
Date: 10 Apr 2023 AS Unit 1 Topic 1
So what do you think: A WELCOME or UNWELCOME VISITOR ?
• EssayEssay
How does El Nino and La Nina affect How does El Nino and La Nina affect weather patterns? (10 marks)weather patterns? (10 marks)