Why was the mushroom cloud flat and China vertical when the first atomic bomb in the United States exploded? Is it an equivalence problem?

One is the different shooting time, the other is the problem of distance and angle, and the third is the problem of quantity. You often see photos of China's first atomic bomb. I estimate that the picture was taken long after the atomic bomb exploded (according to the height estimation of the color and shape of the mushroom cloud)

If you often look at some pictures of nuclear bomb explosions, it is easy to see that the mushroom cloud is the flattest shortly after the nuclear bomb explosion, and it will change after a period of explosion. Besides, it has something to do with the weather. For example, a nuclear bomb that explodes on an island in the United States will form mushroom-like clouds in the sky because of the spread of shock waves, which can lead to mushroom clouds of different shapes.

Of course, the equivalent will also have an impact, and so will the terrain.