Describe El Niño and La Niña and their global atmospheric impacts.

Describe El Niño and La Niña and their global atmospheric impacts.

• A. El Niño is cooling of central/eastern Pacific waters; La Niña warming; opposite effects.
• B. El Niño is warming of central/eastern Pacific surface water that disrupts global weather patterns; La Niña is cooling of those waters, often with opposite effects.
• C. They are only regional phenomena with no global impact.
• D. They occur due to changes in the Atlantic Ocean.

Answer: (B)

El Niño and La Niña are opposite phases of a global climate pattern that ties Pacific Ocean surface temperatures to atmospheric circulation. During El Niño, the surface waters in the central and eastern Pacific warm above average, which weakens the regular easterly trade winds and shifts much of the convection and rain eastward. This disturbance in where heat sits in the ocean and how the atmosphere responds then alters weather patterns around the world—leading to wetter conditions in some places and droughts in others, changes in monsoon behavior, and shifts in jet streams and storm tracks. In contrast, La Niña brings cooler-than-average surface temperatures to the same central/eastern Pacific region. The stronger trade winds enhance upwelling and push convection toward the western Pacific, producing a set of weather effects that tend to be opposite to those seen during El Niño. So you get different rainfall patterns, moisture transport, and storm behavior globally, with many regions experiencing the opposite anomalies compared with the El Niño phase. These fluctuations in ocean temperatures and the resulting atmospheric responses explain the global reach of El Niño and La Niña, far beyond the Pacific basin.

El Niño and La Niña are opposite phases of a global climate pattern that ties Pacific Ocean surface temperatures to atmospheric circulation. During El Niño, the surface waters in the central and eastern Pacific warm above average, which weakens the regular easterly trade winds and shifts much of the convection and rain eastward. This disturbance in where heat sits in the ocean and how the atmosphere responds then alters weather patterns around the world—leading to wetter conditions in some places and droughts in others, changes in monsoon behavior, and shifts in jet streams and storm tracks.

In contrast, La Niña brings cooler-than-average surface temperatures to the same central/eastern Pacific region. The stronger trade winds enhance upwelling and push convection toward the western Pacific, producing a set of weather effects that tend to be opposite to those seen during El Niño. So you get different rainfall patterns, moisture transport, and storm behavior globally, with many regions experiencing the opposite anomalies compared with the El Niño phase.

These fluctuations in ocean temperatures and the resulting atmospheric responses explain the global reach of El Niño and La Niña, far beyond the Pacific basin.