This time of year is peak fog season in San Francisco.

Here’s the science: The so-called marine layer is cold, moist air that’s chilled by the offshore ocean current of water fresh from Alaska. It is at peak contrast with the air over the much warmer land in the summer months. Since warm air rises, the parts of the Bay Area that routinely hit the 90s or 100s literally suck the marine layer onto shore during the afternoon hours, with the cooler air rushing in to replace the rising warm air inland. When the temperature starts to cool in the early evening, the fog bank rolls in. By mid-morning, the sun heats up the fog, usually burning it off by noon, eating away at the delicate clouds with wisps of warm, dry air. It’s a dance of relative humidity that’s made the Bay Area’s unique geography famous. The city of San Francisco, smack in the middle of the Bay, is right in the middle of all the action.

Christophe Tauziet, a product designer at Facebook and San Francisco resident, told me that Sunday night’s fog was the perfect time to test-fly his new drone.

Did you need to get any kind of special permit to operate the drone in San Francisco?

I’m not aware of any regulation that prevents you from flying in San Francisco, as long as it’s for recreational purposes and not commercial purposes (in which case you need a certificate).

What motivated you to try to get this shot last night?

I’ve always been fascinated by the San Francisco fog. (People call it Karl, and it actually has popular Twitter and Instagram accounts.) It’s always very dense, and it travels around the city very fast and usually arrives downtown in the early evening and leaves early in the morning. In the afternoon, I can see it sitting on Twin Peaks from my apartment in a big building at the top of Nob Hill. It looks like if it were sleeping. I sometime put a camera on the roof and record a timelapse of it taking over or leaving downtown.

Yesterday night, as I was watching it rolling over the city and surrounding my building, I thought it’d be nice to try to fly my drone from my rooftop and try to go above the fog to catch the last rays of sun before sunset (what photographers call golden hour).

Were you able to watch the video in real-time as it was shot?

Yeah, my drone has a Wi-Fi extender that streams the video in real-time down to my iPhone, so I can see what the drone is shooting, and can tilt the camera. It’s also very useful when you lose eye contact and try to figure out where the drone is.

Were you nervous when you lost sight of the drone above the fog bank?

A bit, yeah. Usually I’m not, since it’s very common to lose eye contact with your drone when you try to fly above 500 feet, as it’s a fairly tiny drone, but it was very windy (it usually is when the fog rolls over the city) and I lost the video signal as the drone was reaching the higher part of the fog, so I was afraid it would be carried over by the wind and go too far. Usually it’s not a very big problem since these drones are GPS-equipped and can travel back to their starting point by themselves when they lose contact with the controller, but I still feel a bit worried whenever I lose the video signal.

What was your reaction once you were able to see how impressive the video turned out to be?

As I was flying, I actually had a moment where the video signal came back and I could actually see what the drone was filming, so I took advantage of it and tried to move around and play with the fog. But then I lost the signal again and decided it was time to bring it home (it was also super cold). When I came back to my apartment, I was super eager to see the videos, as I knew it could be pretty epic. It turns out I had some great footage, and I couldn’t wait to start editing a little video out of it.

Tauziet has more amazing drone photography on his website.