Lesson 5 - ENSO Cycles + Normal Year Flashcards
What is the El-Nino-Southern Oscillation (ENSO) ?
Naturally occurring mass of warm seawater in the Equatorial Pacific
Where is the ENSO usually located + why?
Western Pacific
‘Pushed’ West by variety of natural factors
Which physical factors ‘push’ the ENSO West?
Ocean Currents
Walker Cell
Trade Winds
How often does this cycle reverse + what is the impact?
Roughly every 7 years
ENSO locates in Eastern Pacific
Which weather conditions does the presence of ENSO result in?
Higher rates of evapotranspiration result in increased precipitation
Which weather conditions does the absence of ENSO result in?
Drier, arid, high pressure zones
What are the 2 ENSO phases known as?
El Nino
La Nina
What type of conditions does El Nino usually trigger + where?
Very dry, drought, monsoon failure
South East Asia, Eastern Australia, Central America + South Eastern USA
What type of conditions does La Nina usually trigger + where?
Drought
West coasts, especially South America
How does the ENSO cycle begin in a normal year?
Pacific trade winds circulate around Walker Cell
Winds travel Westwards
Warm water pushed towards West Coasts
What occurs in the Eastern Pacific Ocean during a normal year?
Shallow thermocline
Large amounts upwelling
How does a normal year affect weather in the Western Pacific?
Warm moist air rises
Creation of low pressure area + heavy rains
How does a normal year affect weather in the Eastern Pacific?
Western air circulates + sinks
Cool + dry conditions
High pressure zones
