I was sitting in the hot tub, watching the stars and airplanes. a lot of airplane traffic above me because of my proximity to bwi. then i saw the v shaped lights through cloud cover, so it was higher and further than local plane traffic. it surprised me because it seemed far away but was much larger than any other traffic i'm used to seeing. and the lights were unlike lights on any plane i've seen. both sides of the v were lit with individual lights, maybe 5-8 each side. no light was brighter than the other, and there were no other lights except on the "v". nothing in the center. it was flying away from me roughly south. it flew at a steady pace, and disappeared into the clouds. i've watched a lot of air traffic around here, and also grew up near george afb in california. this looked nothing like anything i've ever seen, though i did feel like it was terrestrial - it flew like you'd expect an airplane to fly, steady and unchanging. it was only visible for about 10 seconds, emerging from the clouds and then disappearing back in.