A composite of several real-life balloon trips (Glaisher is real and Wren is fictitious, but likely based on the flamboyant French balloonist Sophie Blanchard), “The Aeronauts” has a natural buoyancy that mostly resists the drag of its earthbound flashbacks. Stuffy scenes between James and his parents ( Tom Courtenay and Anne Reid ) alternate with his entreaties for money from the Royal Society, where his bewhiskered fellow scientists think he’s a hoot. After a few of these interludes, neither we nor the movie can wait to get back in that basket with Amelia.

Structural road blocks aside, “The Aeronauts” is that rare adventure movie to celebrate the silence in which its wonders unfold. The cloud of butterflies that magically appears, and the flakes of snow that hover, seemingly stationary, around the balloon during its too-swift descent, are permitted to linger quietly on the screen and in the mind. At one point — in the film’s most terrifying sequence — as Amelia climbs up the balloon’s exterior to release a perilously frozen gas valve, George Steel’s cinematography has such a hushed and blinding beauty that it would be a crime to close your eyes.

Equal parts dizzying and dippy, “The Aeronauts” is family entertainment at its most charming and chaste. By and by, you realize you’ve been watching a romance blossom without a single kiss, but that shouldn’t be a surprise: What James and Amelia are really in love with is the sky.

The Aeronauts

Rated PG-13. Vertigo medication all around. Running time: 1 hour 40 minutes.