Green Craft hovering, then disappearing.On Saturday, May 14th, I and a friend were traveling Westbound on I-80, when I spotted a green object traveling Northbound very smoothly through the air, my best guess is that it would have been directly over the city’s tall building. At first I just thought, “That’s a weird color for a helicopter” because it was traveling just about the same speed as the constant helicopter buzz from the local hospitals.The object was Dark green on the inside and Light green towards the outside and triangular in shape. I spotted the object for about 30 seconds, before the top of the craft seemed to have gone behind the closest cloud cover. However, these clouds were a solid 10,000+ feet high. Once the top of the craft had disappeared the entire craft seemed to morph into itself and disappear completely. After moving my head in every direction to see if it was a reflection from another light, since I was looking through the car window, I could not come up with anything. After the craft disappeared my friend who was driving the car shouted, “Did you see that???” He is a huge disbeliever in UFO activity, and usually calls me crazy or worse when I bring stuff up like this. Once he described exactly what I saw since we didn’t say anything when we first saw it, I knew we both saw the exact same thing.This was mine and my friends first UFO encounter, we are still a little freaked out by what we saw, but wanted to let others know in case they saw the same thing.