There is a cigarette on the box. It smokes at both ends. But the smoke coming out through the mouthpiece goes down

There is a cigarette on the box. It smokes at both ends. But the smoke coming out through the mouthpiece goes down, while on the other side it curls up. Why?

Yes, the smoke is the same, but over the smoldering end of the cigarette there is an upward current of heated air. The air passing with the smoke through the mouthpiece has time to cool and is not already carried upward, and since the smoke particles themselves are heavier than air, they go down.