AI Summary

In the 1600s Peruvian fishers observed that during certain Christmas‑season years the coastal waters warmed and anchovy catches dropped, a pattern they named “El Niño” after the Christ child. The name reflected the seasonal timing of the phenomenon. In the early 20th century physicist Gilbert Walker noted that the low atmospheric pressure and rainy weather over the western Pacific alternated with high pressure and dry conditions over the eastern Pacific. This pressure flip was the first scientific recognition of the El Niño cycle.

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