el niño –southern oscillation
(ENSO)
A periodic failure or reversal of the prevailing westward-blowing winds in the tropical Pacific ocean which increase the temperature of the surface waters in the eastern Pacific, disrupting weather patterns in many parts of the world. Abnormally cold surface waters in the tropical eastern Pacific are called la niña.
This definition is abridged from A – Z of tree terms: A companion to British arboriculture.
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