As i was riding home from school, i was at a red light. i looked at the target and saw this grey cloud colored thing with no noticeable detail, flying in a direction. when i first saw it, i thought it was a plane at a position where i couldn't see the wings. after i spotted it, the thing increased and decreased elevation while going forward without changing angle. i had a WFT moment. then it went behind a cloud and it was gone. this all happened within a minute.