Snow screen

If you're walking home in a freezing wind at 8.00 pm and it starts to snow, it's as well to be carrying a freshly cooked pizza - using both hands, obviously. (Those cardboard boxes are quite good. It was still hot - well, hot enough - when I got it home.)
Six hours later, the wind has dropped, the sky has cleared, the moon is up and the snow is still on the ground and clinging to the plants.

This is the screen door at the back of the house. It's intended to keep flies out. It also keeps snow out.
It was a toss-up between this and the helicopter.

About the helicopter...
For days now, every afternoon, it's turned up and hovered (with a bit of drifting about) for long periods (like an hour), roughly above the highway near us, pointing west. It has an obvious camera affair hanging under its chin.
It doesn't have any discernible identification, other than the usual numbers - no TV station logos, no Westpac or Careflight or Police or any of the other likely suspects.
What's it doing?