Wet-Down

A dry road at night is black. It absorbs every light you put on it and the bottom half of the frame goes dead. Soak the same road and it becomes a mirror, so every lamp, sign and headlight is in the shot twice.

It is the cheapest way to make a night exterior look lit. The lights were already there, and the wet ground is what puts them in the picture.

A water truck or a hose soaks the surface before the take, and the crew re-wets between takes as it dries. The ground has to stay wet for the whole shot, because a road drying halfway through reads as a continuity error.

Reflection depends on angle. A low camera sees more of it than a high one, because the surface behaves like a mirror and a shallow angle catches the sources across the road rather than the ground underneath them.

Texture matters. Smooth tarmac gives long clean streaks of light. Cobbles break the same reflection into hundreds of small highlights, which is a different picture from the same lamp.

Use it on any night exterior with practical light in it. This is standard practice rather than a special effect.

Skip it in daylight, where the sky is already doing the lighting and a wet surface adds only glare.

Rain has falling water as well as the soaked ground. A wet-down has the ground and clear air above it, so say that no rain is falling.

A shot after rain is a wet-down by another name. The difference is only what the scene claims happened, because the picture is the same.

Rain falls anyway. Any wet street in a prompt tends to pull rain in with it, so state that nothing is falling and that the sky is clear.

The second failure is a damp road with no reflection. Ask for mirrored highlights and name the lights that should land in them.