Hadley Cells are large-scale atmospheric circulation patterns that occur in tropical regions. They form due to the intense heating of the Earth's surface by the Sun, causing warm air to rise near the equator. As this air rises, it cools and loses moisture, leading to the formation of clouds and precipitation. Once the air cools, it moves toward the poles at high altitudes before sinking around 30 degrees latitude. This descending air creates areas of high pressure, resulting in dry conditions and deserts. Hadley Cells play a crucial role in global climate and weather patterns.