Rebecca Morelle has written a piece for the BBC explaining that scientists have figured out how snakes can glide through the jungle:
Prof Socha said: “As it jumps, it flattens out from just behind the head to where the tail starts. What it is doing is taking its ribs and rotating them forwards toward the head and upwards toward the spine.”
The snake actually doubles in width and “creates a unique cross-sectional shape” which aids in the gliding. The accompanying video and photos are worth a look.