8: Global Circulation and El Niño
- Page ID
- 50834
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As discussed in previous investigations, temperature and precipitation are among the most influential factors in a location’s climate. They differentiate a hot, dry desert from a cold, wet subpolar forest. Both temperature and precipitation are strongly influenced by many factors, several of which we have already discussed, such as topography, latitude, and ocean currents. One factor, however, that still needs to be covered in greater depth to understand its influence on climate is wind. It may be argued that wind can often be the single biggest factor in a location’s climate. Wind patterns often determine which regions get rain and which don’t. Wind drives global ocean currents, transporting heat to different parts of the planet. Wind also moves warm air masses towards cooler regions, and cooler air masses towards warmer regions, fueling storm systems and causing drought, heatwaves, and even wildfires. Figure \(\PageIndex{1}\) shows a schematic of global wind circulation and the names of common wind patterns.
In this investigation, let's focus on how wind works, how it factors into Global Circulations, and how it can be responsible for Global Climate Variability.
- To determine planetary-scale wind directions.
- Distinguish between the single-cell and three-cell models of global circulation.
- Define the Walker Circulation and the El Niño Southern Oscillation.
Investigation 7 has 25 questions in total, and the list is continuous, carrying over from the first to the last subpages of the investigation.
- 8.1: Why the wind blows
- This page explains the forces influencing wind according to Newton's laws of motion, detailing three key forces: the Pressure Gradient Force, which drives wind from high to low-pressure areas; the Coriolis Force, which affects wind direction; and Frictional Force, which slows wind. An analogy using water in tanks illustrates the Pressure Gradient Force, and a weather map helps readers to recognize pressure differences and anticipate air movement.
- 8.2: Other forces acting on the wind
- The Coriolis Force is caused by Earth's rotation, which affects wind direction differently in the Northern and Southern Hemispheres. Its relationship with the Pressure Gradient Force leads to geostrophic flow. Additionally, the impact of surface friction on wind behavior is crucial to weather patterns and atmospheric circulation.
- 8.3: Atmospheric Circulation
- We introduce the atmospheric circulation models, beginning with a simple single-cell model that illustrates wind patterns due to differential heating of the Earth. The more complex three-cell model accounts for Earth's rotation, detailing the Hadley, Ferrell, and Polar cells and their effects on climate and ecosystems.
- 8.4: El Niño-Southern Oscillation
- This page discusses the Walker Circulation, which describes the interplay between atmospheric and oceanic conditions in the equatorial Pacific, influencing weather patterns and leading to phenomena like El Niño and La Niña. It highlights the role of the TAO/Triton buoy array in monitoring these changes.
- 8.5: Accessible Descriptions
- This page provides accessible descriptions for the images in the Investigation.
Thumbnail: Idealized depiction of large-scale atmospheric circulation on Earth. Earth Global Circulation by Kaidor is licensed under CC BY-SA 3.0