What are the Ferrel and Polar cells and how do they interact with Hadley cells?

• A. Ferrel cells circulate between the equator and 30° latitude with easterlies; Polar cells operate from 30° to the poles with westerlies; they do not influence Hadley cells
• B. Ferrel cells are tropical; Polar align with Hadley
• C. Ferrel cells circulate between ~30°–60° with prevailing westerlies; Polar cells operate from ~60° to the poles and align with easterlies; collectively drive mid-latitude weather
• D. Ferrel and Polar cells replace Hadley cells in the upper atmosphere; they do not interact

Answer: (C)

The idea being tested is how the three-cell model of atmospheric circulation works and how the cells interact to shape mid-latitude weather. The Ferrel cell sits in the mid-latitudes, roughly from about 30° to 60° latitude, and its surface winds are prevailing westerlies. Air tends to rise around the 60° region where it meets cooler polar air, and descend around the 30° region, where air from the subtropics sinks. The Polar cell spans from about 60° latitude to the poles, with surface easterlies and cold, dense air sinking near the high latitudes.

Together with the Hadley cell, these three circulating systems transport heat from the equator toward the poles and organize the global wind belts and storm tracks. The boundaries between cells—particularly around 30° and 60°—are where storms and jet streams tend to form, which is why mid-latitude weather is so dynamic and tied to the interactions among these cells. This description matches the statement that Ferrel cells operate roughly from 30°–60° with westerlies, Polar cells from about 60° to the poles with easterlies, and, taken together with the Hadley cell, they drive mid-latitude weather.