Why can you see emission in jet plane and not in airplane?

In a jet aircraft, the contrails are created by the exhaust emitted from the engines condensing in the freezing atmosphere. Since the air is so frigid at +30,000 ft, the emissions crystallize almost instantly, creating a distinctly visible trail behind the aircraft. On an airplane, the momentum is created by a series of props that pull (or push) the craft forward, creating little to no exhaust to freeze. Also note that airplanes cannot generally fly as high as jet aircraft due to their inefficient propulsion system(s), thus the air is not near cold enough to crystallize what little emissions are created.