Air balloon

For the last days I've taken the car to work and missed a lot of those opportunities for blipping I get when I take my half hour walk. When rushing from house to car I heard some weird noise. I lifted my eyes and saw this air balloon. They use to be very colourful, but this was actually black with some yellow pattern on top. Disregard a hizzing sound from time to time it glide silently through the air.