Final answer:
The movement of air in Hadley cells is primarily driven by unequal heating of large masses of air and the rotation of the Earth. The water cycle also plays a role in the movement of air in Hadley cells.
Step-by-step explanation:
The movement of air in Hadley cells is primarily driven by unequal heating of large masses of air which creates air movements. This leads to the flow of hot air from the tropics to the poles and the flow of cold air from the poles toward the tropics. Another driving factor is the rotation of the Earth, which causes the observed easterly flow of air in the northern hemisphere.
Additionally, the water cycle plays a role in the movement of air in Hadley cells. When the Sun heats the water on the Earth's surface, it evaporates and rises into the atmosphere as water vapor. As the water vapor cools, it condenses and falls back to the Earth as precipitation, completing the cycle.