Sure, folks discuss the weather a lot, especially in Britain. Still, it’s hard to imagine that a quiet chat about the weather — and why it isn’t boring — could be an emotional high point of a feature film. Especially when that film is about World War II, one of the most cinematic subjects in history. But that’s before you watch Andrew Scott, who could make the phone book sound exciting — or at least, poignant and nuanced. People often talk about whether it’s raining, his character, Capt. James Stagg, argues at one point in “Pressure,” the story of how meteorology saved D-Day. But do they consider WHY it’s raining? Or, what actually makes it windy? And how, he asks, can that be boring? There are times when “Pressure,” directed and co-written by Anthony Maras, feels like a series of similarly elegant speeches. That makes some sense, since it’s based on a play — the 2014 drama by David Haig. Telling the relatively little-known story of how forecasters made the crucial call of when to land on Normandy’s beaches, the film pits two men against each other: Scott’s introspective, stubborn, even sour meteorologist, and none other than Dwight D. Eisenhower, celebrated general and future president, played by Brendan Fraser.