Getting the right shot can sometimes take hours, maybe even days. But what about years? That's the case with Simon Christen's gorgeous time-lapse video Adrift, which is at least two years in the making. If you've ever wondered what it might feel like to hover among above the clouds around the San Francisco Bay Area, this video is about the closest you're going to get:

The music was custom-written for the piece by Jimmy LaValle of The Album Leaf, and you can actually license any of this footage directly from Simon by going to his website. Here is a little of what Simon wrote on Vimeo describing the process:

The weather conditions have to be just right for the fog to glide over the hills and under the bridge. I developed a system for trying to guess when to make the drive out to shoot, which involved checking the weather forecast, satellite images and webcams multiple times a day. For about 2 years, if the weather looked promising, I would set my alarm to 5am, recheck the webcams, and then set off on the 45-minute drive to the Marin Headlands.

I spent many mornings hiking in the dark to only find that the fog was too high, too low, or already gone by the time I got there. Luckily, once in a while the conditions would be perfect and I was able to capture something really special. Adrift is a collection of my favorite shots from these excursions into the ridges of the Marin Headlands.

He mentioned his technique and gear in the comments (all photos were captured in manual mode):

I am using a canon 7D and canon 40D and try and capture as much footage as possible.
Depending on exposure time, it's usually between one picture every 2-10sec. This way individual images of the fog still connect to each other and produce a nice smooth motion.
I'm shooting in the highest resolution possible with both cameras and in RAW.
Most shots in this video are trimmed and are much longer in its original form. So each shot is usually between 2-4 hours of shooting.

If you missed his last video The Unseen Sea, check it out:

If you're feeling generous, be sure to head on over and donate to his tip jar, which will go towards helping him put out more beautiful videos.