Clouds of Venus (Free Space trilogy, #1)

Dale Kinmont is a college student in post-catastrophe America. He's lucky; he lives in one of the walled cities for the nation's elite, and life is pleasant. He expects to graduate and find employment in his uncle's company.

Everything changes when he's framed for murder. He's tried, convicted, and sentenced to hard labor in the prison colony on Mercury.

He ends up in Hesperus instead, a flying city that soars eternally through the acidic skies of Venus. His goal now is to find a way to clear his name and return to Earth before Hesperus erupts in civil war. He also must battle the harsh realities of the planet itself. Because if the Hesperans don't kill him, Venus probably will.