Research laboratories conduct a wide range of experiments using balloons. Science payloads may weigh anything from a few hundred grams to several tonnes. And balloons may be required to operate at an altitude as low as a few hundred metres or as high as 40 km.
Infrared Montgolfiere balloons are derived from zero-pressure stratospheric balloons. Lift is provided by air heated by the Sun and by infrared radiation from Earth. They are also capable of long-duration flights.
Superpressure balloons are sealed and their envelope is stable enough for long-duration flights.
All these balloons obey the same laws of physics governing a bag filled with gas and left to its own devices in the atmosphere.