Why does the smoke from a factory not keep rising forever?

The smoke from a factory does not keep rising forever due to a combination of factors, including gravity and the cooling of the smoke. As the smoke rises, it disperses into the surrounding air, losing heat and buoyancy. Eventually, the smoke reaches a point where it cools down enough to descend, and environmental factors like wind and atmospheric conditions can also influence its dispersion. Additionally, pollutants can settle out of the smoke, further reducing its visibility and height.