Son of Flubber (1963)

sequel to The Absent-Minded Professor (61).
Professor Brainard (Fred MacMurray) and Biff Hawk (Tommy Kirk) fly into Washington DC in Brainard's flying Model-T Ford, and the expectation is that they will receive funds for Brainard's Flubber formula to pay off Medfield College's debt. But, they're in  for a rude awakening: DC bureaucracy delays the money indefinitely (epitomized by Edward Andrews' mouthy politician). Back home, Brainard and his wife (Nancy Olson) are besieged by opportunists, the private sector which plans to market Flubber in every way possible. Brainard repels them with the news that the government has his formula locked up. Then, the IRS pays him a visit, with a big bill for the projected huge profits he will enjoy. Brainard takes all these setbacks in stride but the wife is getting fed up. It doesn't help that Brainard's rival for his wife's affections shows up again with a lady from Brainard's past.
As far as Brainard's invention, he decides to adjust its properties to create his own rain clouds - for whatever reason, his objective now is to control the weather.