[IAmATeaf]

Noticed over the last few weeks that when it rains my headlights appear to fluctuate and pulsate, I can see this when I pull up behind a car in traffic. Headlights are xenons and I’ve never ever seen this in any of my cars before. It’s almost like the rain is flowing over the lens and is disrupting the light output, anybody seen or noticed anything similar?

[f36_MSport]

Hi there, I just had the same observation a couple of days ago. I bet this is due to water flowing in front of the lights because I only am able to spot that when I am against an obstacle (and obviously I am braking) so I guess the water flows down from the hood.

When I go out and look at the lights (while I hope no one thinks I am crazy) I don't see any pulsations.

[IAmATeaf]

I did think it was the rain causing this but I’ve never ever seen this with any other car I’ve had. Maybe water on the bonnet is being directed straight over both headlights?

[Fliplegend]

It's the rain drops. Happens to many cars. The nicer the headlights, the more noticeable.

[Billfitz]

Beam scatter is common with HID. It's why they have wiper/washers, as even dirt on the lenses will cause beam scatter.