Yosemite.2

Actual Elapsed Time: 17 minutes (1,000 seconds)

Afternoon clouds form and disappear over Yosemite Valley. Clouds appear when water vapor in the air is cooled and forms tiny droplets. These droplets are too small to fall to earth as rain but they reflect light, which gives a cloud its distinctive color. When the air inside the cloud is warmed, in this case by the sun-baked granite walls of Half Dome peak, the water droplets are turned back into water vapor and the cloud disappears. The water is still there, it's just in a form that doesn't reflect light. In most situations, clouds don't move or form quickly enough for us to see these changes. But by speeding up this scene 100 times, we can see how clouds, and the water inside them, change over time.

How This Clip Was Made:

This time-lapse video was created by shooting 17 minutes of regular video. Only 1 of every 100 frames of video was digitized and transferred to a computer. When displayed, the remaining frames show the action at 100 times normal speed. Production: Bob Hone. Post-Production: Brennan Doyle.

Related Clips:

Yosemite.1 - Actual Elapsed Time: 1 minute (60 seconds)

Yosemite.3 - Actual Elapsed Time: 3.5 hours (13,000 seconds)