2 nearly vertical contrails seen.I had finished shopping and was sitting on the hood of my friends' car waiting for him and noticed two contrails in the southeast. The one to the right was thickening and was obviously older but the one to the left was still being generated by a small silver object.I've seen hundreds of contrails but I have never seen any that were nearly straight up and down. The object continued making the contrail and then disappeared. It was partly cloudy and I assumed it went behind clouds but the contrail just stopped. It was gone.My friend finally came out and I pointed the contrails out to him. He wasn't very impressed.((NUFORC Note: If an a/c, generating a contrail, flies directly overhead a witness, and it flies to the horizon, the contrail will appear to "go down." However, the a/c probably was in level flight. PD))