Bay Effect Clouds

A cool video by way of WaPoo, How the Chesapeake Bay became a cloud-making factory Wednesday

Out of thin air, rows of clouds formed in a long line, streaking over the main channels of Chesapeake and Delaware bays, almost as if hand-painted.

The fast-flowing streams of clouds made for a stunning scene on weather satellite imagery. But how did this spectacle occur? Take Arctic air, and blow it over a long fetch of warm water, and you manufacture clouds.

It began with the record-setting frigid air pouring over the relatively mild waters of these bays — setting up a critical contrast for cloud formation. Air temperatures were in the 20s and 30s, whereas the bay waters were in the mid-50s. The warm air at the water’s surface, less dense than cold air rushing over it, was then able to rise, cool and condense into clouds.

But for the clouds to line up along the entire lengths of both bays, which is somewhat rare, the cold air had to enter at just the right angle and pass over the water for a sufficiently long distance to give clouds time to form.

Pretty cool. Pun noticed, if not intended.