Final answer:
The El Niño phenomenon describes the unusual warming of surface waters in the eastern tropical Pacific Ocean caused by weakened trade winds. In contrast, La Niña is characterized by unusually cool ocean temperatures while a monsoon and a tornado refer to entirely different weather patterns.
Step-by-step explanation:
The climate pattern that describes the unusual warming of surface waters in the eastern tropical Pacific Ocean is a) El Niño. This phenomenon occurs when the trade winds that usually push warm surface waters towards the west weaken. As a result, warmer water flows back to the east, causing an increase in sea surface temperatures. This can disrupt normal weather patterns and cause extreme weather events in parts of the globe.
On the other hand, La Niña is characterized by unusually cool ocean surface temperatures in the central and eastern tropical Pacific. A monsoon is a seasonal wind pattern and a tornado is a violent and dangerous wind storm, both of which are fundamentally different from El Niño.
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