Chrysopelea launches from a branch by forming a J-shape with the front of the body and pushing off. In the air it splays its ribs outward and flattens the belly, turning a cylindrical body into a wing-like section roughly twice the resting width, concave underneath.
The aerial undulation was long assumed to be a habit carried over from crawling. Motion-capture work by Yeaton, Socha and colleagues, published in 2020, tracked snakes gliding through a large arena and used the data to build a physical model. When the undulation was removed from the simulation the modelled snake became unstable and tumbled; with it, the body stayed on a stable glide path. The wave appears to distribute the aerodynamic forces along the body and damp rotation.
The result is a glide, not powered flight. Snakes lose height throughout, and reported glide ratios are modest, though animals launching from higher points travel considerably farther horizontally. Steering appears to come from changes in body posture rather than from any control surface.