El nino and la nina

• El nino is the southern oscillation
• El nino is a sequence of events that occur naturally every 2 to 7 years but now occurs more frequently, partly due to climate change
• Normal conditions of "trade winds" blow westwards near the equator, this moves surface current in the same direction
• Trade winds allow deep cold water to be drawn up to the surface near south america, this is rich in nutrients and causes large algal blooms
• Algal blooms are able to support rich food webs
• The current in normal conditions continues westwards past South america this becomes warmer as it travels, this brings a warm current along to austrailia
• Currents affect rainfall patterns, e.g. water temperature is a determinant to where rain is able to fall
• In el nino years, surface winds that create currents change direction so that ocean currents slow or reverse
• In el nino years, this prevents retrieval of nutrients causing collaspe of rich food Web in South america
• In el nino years there is a change in distribution of precipitation
• El nino can cause drought, fewer hurricanes, fewer tropical cyclones
• La nina occurs when winds blow stronger in the normal direction so water currents speed up and temperature difference between Western and easternEastern Pacific increase
• If human activity is involvedin effect, it may mean global weather patterns may become more unpredictable