Would temperature in the upper troposphere and the stratosphere be comfortable for people?

No, temperatures in the upper troposphere and the stratosphere are not comfortable for humans. In the upper troposphere, temperatures can plummet to around -50 to -60 degrees Celsius (-58 to -76 degrees Fahrenheit), while the stratosphere can reach even colder temperatures. Additionally, the lack of breathable oxygen and the presence of harmful radiation make these altitudes inhospitable for human life without specialized equipment.