I move in London this January and found it was easy to see many beautiful vapor trails of airplanes in the sky of London. Although we can see them in Japan, they are fewer than ones in London. I love them and I took many photos of them. I wondered why I could see them so many in London. I thought that there might be more are traffic in London because London is one of the world famous big city. But I did not agree this idea because Tokyo is one of them but does not have so many vapor trails of airplanes. Recently, I did not see them in London as many as I saw. I did not care the fact.
It was cold morning yesterday. I found that my breath was turned into white smoke when I went to my job. I looked up the sky and there were many l vapor trails of airplanes. Aha! I understand that the cold air helped them make clear. It is natural that we see it more in the UK because the UK is colder than Japan and I saw them clearer in winter because it was cold.