If you look at the world map -- it's easy to see this -- you'll see that there are forests in the equatorial zone, and deserts are organized at 30 degrees north latitude, 30 degrees south latitude, aligned.
如果你看到这幅世界地图 你很容易看到 在赤道带有片片森林 而沙漠则聚集在北纬30° 以及南纬三十°，排成了一条线