Little boy 

Sounds so harmless, doesnt it? 

Hot summer afternoon swimming in the Hurunui River

So far this summer, Canterbury weather has been a beachgoers dream.  Long warm summer days, perfect for camping and swimming. 

However in many parts of the world there is inclement weather causing many fatalities and having worldwide affects.  In the last few weeks there has been flooding in England, South America and midwest USA, a hurricane in Scotland, tornadoes in USA, a cyclone in Iceland and freakishly warm weather at the North Pole and California...in winter!  All this is after the hottest July on record and possible hottest year ever. 

The main cause of all of this is "little boy" or El Nino.  The El Nino Southern Oscillation is a shift in the normal weather patterns which occur every two to seven years.  Normally trade winds blow towards the west from tropical South America to Southern Asia, pushing warmer water into the western Pacific. This pulls an upwelling of colder water from deep in the ocean along the South America Pacific coastline.  The warmer water warms the air, which rises and forms moisture laden clouds and unsettled weather.  When the air has cooled and dried it then blows back across the pacific in the upper atmosphere and descends at the eastern Pacific. 

If the westerly trade winds weaken, El Nino conditions arise.  Less warm water is pushed into the western Pacific, less cold water upwells from the ocean along South America.  The lack of wind warms the tropical mid Pacific water more than usual and causes the unsettled moisture laden air to move across to the mid Pacific and the cooler, drier air to descend in the western Pacific.  This change effects the temperature and weather systems across the whole planet.   

Typical El Nino weather patterns include more tropical storms in the south west Pacific, higher rainfall in South and North America and parts of Africa and lower rainfall in Australia and India which can cause extreme draught.  New Zealand usually experiences a drier than normal east coast and wetter than normal west coast.

El Nino can have serious affects on economies, typically in Asia and the Pacific as well as causing fire, draught, flooding, and is believed to be partially responsible for historical famine and plague.  All this from a little boy!