The air inside the balloon is heated by greenhouse effect and the black screens pick up the energy that has gone through the transparent polyester film.
Hot Air Balloons!
Balloons and Blimps
pretty solar balloonsMore
Long solar balloonMore
Solar Balloons attached to cablesMore
Solar balloon. A gas burner is fitted to ease the inflation, or to cope with the possibility of cloud cover during the flight. The altitude control is done by the opening or closing of horizontal panels located at the balloon equator.More