Most of the exterior scenes were filmed in the early-morning in Los Angeles, within a hazy light that is glaring and gloomy at once.
This atmospheric effect is commonly called an "inversion layer," which is a reversal of the normal decrease of air temperature with altitude. The cooler air is near the surface, and the air gets warmer as the altitude increases.
It's upside down.
The story's protagonist, Theodore Twombly (Joaquin Phoenix), is a man living in an inverted universe. While on the rebound from a failed marriage, Twombly begins a relationship with an operating system.
Her doesn't have a lot of gadgets and technology, but everybody seems to be interacting with an operating system of their own. They walk around in public, singly or in pairs, oblivious, immersed in a different reality.
Children appear in Twombly's gauzy recollections, but when he and Catherine (Rooney Mara) meet in the present to sign divorce papers, he doesn't ask about them.
Twombly climbs a set of stairs and overlooks the beach on one of his dates with Samantha. This mass of humanity would pretty much encourage me to turn around and go home.
Jonze re-visits this theme of climbing stairs at the end of the movie, after Samantha has evolved to the point where she leaves him. Twombly and Amy (Amy Adams) ascend to the roof of his skyscraper apartment building.
Skyscrapers are omnipresent in Her, and though sterile, represent the only aspirational motivation. Everyone else is barren or sterile. As the sun rises and bathes Amy and Twombly in morning light, I was left wondering what it was that prevented him from taking her hand and doing a 40 floor swan dive.
