Smoke from a nearby chimney.
The occasional car.
Near freezing temps.
Clouds moving constantly in front of the sun.
Standing just slightly out of remote range.
Our family portrait session was challenging. Two out of four family members got a bit cranky, and they weren't the little ones. (The little ones were very patient!) I got what I needed, really, within 15 minutes—not too bad. But next year my goal is to have a portrait of people smiling because they're actually happy, and not just faking it for the camera.
(Hubs' face was intentionally modified for security purposes. I could tell you why, but. . . no, actually I couldn't.)