Question

Which of the following is true of El Niño? A) It cools the Pacific Ocean near Peru. B) It causes flooding in Australia. C) It cools the waters off Alaska. D) It may occur when the trade winds slacken or reverse.

Short answer

D is correct; El Niño may occur when the trade winds slacken or reverse.

Step-by-step solution

Understand El Niño

El Niño is a climate phenomenon that occurs in the Pacific Ocean. It involves warming of the ocean surface waters and causes various climatic changes worldwide, including altered weather patterns.

Evaluate Option A

Option A states that El Niño cools the Pacific Ocean near Peru. In fact, El Niño is characterized by warmer than average ocean temperatures in this region, so Option A is incorrect.

Evaluate Option B

Option B suggests that El Niño causes flooding in Australia. However, El Niño typically brings drought conditions to Australia and not flooding, thus making this option incorrect.

Evaluate Option C

Option C indicates that El Niño cools the waters off Alaska. During El Niño, the waters in the North Pacific, including near Alaska, often become warmer, so Option C is incorrect.

Evaluate Option D

Option D states that El Niño may occur when the trade winds slacken or reverse. This is true, as El Niño is often initiated when the trade winds weaken, allowing warm water to move eastward across the Pacific.

Key concepts

Pacific Ocean climate

The Pacific Ocean climate plays a significant role in global weather patterns. This vast ocean covers more than 60 million square miles and influences countries like Peru, Australia, and countless islands. Due to its size and location, the Pacific Ocean affects atmospheric conditions.

One key driver of this climate is the interplay between ocean currents and wind patterns, especially phenomena like El Niño. When the conditions are stable, the Pacific Ocean maintains its usual climate patterns. However, during events like El Niño, these stable conditions can shift dramatically.

• El Niño is marked by warmer sea surface temperatures, which arise every few years and last for several months.
• The phenomenon can influence weather globally, due to changes in ocean temperature and wind patterns.

trade winds impact

Trade winds are essential in maintaining the normal climate of the Pacific Ocean. These winds blow consistently from east to west near the equator and play a critical role in the distribution and regulation of heat and moisture across the ocean.

During a standard year, trade winds push warm water towards the western Pacific. However, if these winds slacken or reverse, it sets the stage for El Niño.

• Weaker trade winds mean less upwelling of cold water from the ocean's depths.
• This results in a warm surface layer that extends eastward across the central Pacific.

The impact of this change in the trade winds can lead to various climatic consequences, such as droughts in some regions and increased rainfall in others.

weather patterns

El Niño significantly alters global weather patterns. This complex climate phenomenon can cause both extreme and subtle deviations from normal worldwide weather conditions.

During El Niño years, some of the most notable changes include:

• Droughts in regions like Australia and Southeast Asia.
• Increased rainfall and storms in South America, particularly along the western coast.
• Altered monsoon patterns in Southeast Asia, affecting agriculture and water supply.

These variances are primarily due to the warm ocean waters impacting atmospheric circulation patterns. Through these disruptions, El Niño can have a profound effect on agriculture, water resources, and natural ecosystems.

ocean temperature changes

Ocean temperature changes are a defining feature of El Niño events. Normally, the eastern Pacific is cooler due to the upwelling of cold water. However, during El Niño, this area becomes significantly warmer.

This warming can:

• Disrupt marine ecosystems by altering nutrient supplies.
• Influence global climate patterns by changing atmospheric pressure systems.

For instance, the warmer ocean temperatures can lead to the weakening of the Walker Circulation, which is a system of east-west atmospheric circulation over the equatorial Pacific.
Understanding these changes is crucial, as they can have wide-ranging effects on global weather and climate, impacting not only marine life but human activities dependent on predictable weather patterns.