Does hot air balloons fly in the troposphere?

Yes, hot air balloons fly in the troposphere, which is the lowest layer of Earth's atmosphere, extending from the surface up to about 8 to 15 kilometers (5 to 9 miles) high. They operate by using heated air, which is less dense than the cooler air outside, allowing the balloon to rise. Most hot air balloon flights occur at altitudes well within the troposphere, typically between a few hundred to a few thousand feet.