The most important weather processes after seasons! El Nino and La Nina The most important weather processes after seasons!

Never heard of them! Where are they? In the Southern Pacific between Australia and South America

So they are nothing to do with Europe? What kind of Summer weather did the UK have last year? That was La Nina!

Note where the Jet Stream usually goes – between Iceland and Norway La Nina Effect 1.The North Atlantic Jet Stream usually passes the U.K. meaning no summer storms. Note where the Jet Stream usually goes – between Iceland and Norway

La Nina Effect 3.The Eastern Pacific was cooler causing higher pressure and resulting in anti-cyclonic conditions. HIGH 4. So was the Caribbean and Atlantic ocean. HIGH 2.This summer was different.

La Nina Effect 7. La Nina means ‘Girl Child’ and usually happens every six years. 5.There was also high pressure over Iceland. 6.The North Atlantic Jet Stream was squeezed between two areas of high pressure, bringing the storms- nice open ocean to pick up moisture. HIGH HIGH Where does the Jet Stream usually go?

OK – So La Nina has an effect But what is it? How is it different from El Nino? What is the normal state of affairs? And WHY those names? We already know that La Nina means girl child – but El Nino? But before we look into that – we need to look at a map of the world

This is an odd looking world map – what is different about it? Look at the compass rose. What country is in the West Pacific? The East Pacific?

El Nino The term El Nino means 'Christ Child' and was first used by Peruvian fishermen in the late 1800's to describe the warm current appearing off the western coast of Ecuador and Peru around Christmas time. This was bad news for the fishermen, as they depended on cool water welling up from the deep carrying nutrients for the fish. No food – no fish! However, that was not all that happened. But more of that later! Let’s look at why?

Now get the WS for today As we go mark on the items mentioned The highs and lows The clouds and rain The warm and cold surface water

This is what normally happens The land in the west is Australia. The winds travel from east to west, taking the warm water with them. The warm wet air rises (low pressure), dragging in cooler air from the east (anticyclone). This brings warmth and rain to the west Pacific. Cool water is dragged up along the S. American coast

All that summer rain in Australia! What do we get from Australia? What do they grow lots of? On the East Pacific, in Chile and Peru, the wind blows away from them. So while the fishermen are happy (cool water = nutrients), the land is generally unproductive – Atacama Desert stretches down the Pacific east coast

El Nino As you see , El Nino starts where the ‘normal’ ends. Then the winds drop and the warm water starts to move east. Then the warm air rises in the East, causing a low pressure. Air moves from the west causing a high pressure. Now the rain fall in the East Pacific

In El Nino time The East Pacific is warm and wet – the Atacama Desert, in general one of the driest places on earth, gets a real soaking – and ‘the desert flowers’ The fishermen suffer! And so do the Australians! Why? El Nino lasts for between 9 and 18 months After that things sometimes go back to normal But at other times La Nina occurs – which is Normal ++

La Nina Notice Normal and La Nina are the same (at the start) But not at the end

La Nina I said it was Normal only more so! I hope you noticed the heavier rainfall! Also that it even colder in the Eastern Pacific than before and this means even less rain than normal there All these pictures were scene shots from an animation that I would now like you to watch It is at http://esminfo.prenhall.com/science/geoanimations/animations/26_NinoNina.html

  El Nino                                                                          

  La Nina                                                                                                                                                                                                                             

El Nino Problems 1982-3 SOUTH and CENTRAL AMERICA BOLIVIA: DAMAGE: $300 million. EFFECTS: Storm related floods. VICTIMS: 50 dead, 26,000 homeless. ECUADOR AND NORTHERN PERU: DAMAGE: $650 million. EFFECTS: Flooding and coastal destruction from high surf. VICTIMS: 600 dead. SOUTHERN BRAZIL, NORTHERN ARGENTINA AND EASTERN PARAGUAY: DAMAGE: $3 billion. EFFECTS: Flooding. VICTIMS: 170 dead and 600,000 Evacuated.

El Nino Problems 1982-3 SOUTH and CENTRAL AMERICA SOUTHERN PERU AND WESTERN BOLIVIA: DAMAGE: $240 million. EFFECTS: Drought. MEXICO AND CENTRAL AMERICA: DAMAGE: $600 million. EFFECTS: Drought. CUBA: DAMAGE: $17 million. EFFECTS: Storm related floods. VICTIMS: 15 dead. GALAPAGOS ISLANDS: EFFECTS: Massive bird migration off of Island. Bird and mammal nests abandoned. Nearly 100% of fur seal pups lost. Ninety-five percent coral reef mortality.

Micronesia

El Nino Problems 1982-3 ASIA INDONESIA: DAMAGE: $500 million. EFFECTS: Drought. VICTIMS: 340 dead. JAPAN: EFFECTS: Oyashio cold current extends further south reducing abalone harvest off the coast of Honshu Island. MIDDLE EAST (MOSTLY LEBANON): DAMAGE: $50 million. EFFECTS: Cold and snow. VICTIMS: 65 dead. PHILIPPINES: DAMAGE: $450 million. EFFECTS: Drought. SOUTHERN INDIA AND SRI LANKA: DAMAGE: $150 million. EFFECTS: Drought. AFRICA SOUTHERN AFRICA: DAMAGE: $1 billion. EFFECTS: Drought.

El Nino Problems 1982-3 UNITED STATES MOUNTAIN AND PACIFIC STATES: DAMAGE: $1.1 billion. EFFECTS: Storms. VICTIMS: 45+ dead. GULF STATES: DAMAGE: $1.1 billion. EFFECTS: Storm related floods. VICTIMS: 50+ dead. NORTHEASTERN STATES: DAMAGE: Incomplete. EFFECTS: Storms. VICTIMS: 66 dead. COAST OF CALIFORNIA: EFFECTS: Torrential rains, winds, and high tides erode coast and dislodge kelp beds. Fishermen find species of marine life that do not belong there, and could not find those that did. Los Angeles has nearly triple the amount of normal rainfall. WESTERN EUROPE: DAMAGE: $200 million. EFFECTS: Storm related floods. VICTIMS: 25 dead. SPAIN AND NORTHERN AFRICA: DAMAGE: $200 million. EFFECTS: Drought

This unit has been about weather systems In particular about low pressure and high pressure What do we call the low pressure systems we have over the UK? And the high pressure systems? What kind of weather do we have when there is high pressure? In what ways might high pressure areas be dangerous for the people who have one? And the weather that goes with low pressure? What can be dangerous about these?

This unit has been about weather systems What sort of pressure do hurricanes have? What sort of weather do they bring? What are the 3 things that make hurricanes dangerous for places like New Orleans or cyclone for places like Bangladesh? About today, I think you will remember that both El Nino and La Nina have high AND low pressures – but can you remember which way round they go? El Nino first – where? – weather – a problem? La Nino – where? – weather – a problem?

That’s the homework! Fill in a table with the information that we have just talked about! And remember it MUST be in before Thursday evening or else your homework grade will go down in your report!