When something really worries or upsets you, you can describe it as disturbing. War photography is usually disturbing.
It can be disturbing to see people be hurt, or a child going hungry: it troubles the person who is witnessing such difficulties. Some strange things are also often described as disturbing, such as bizarre clown art or people who walk around dressed in animal costumes. If it bothers and distresses you, it's disturbing. The Latin root, disturbare, combines dis, "completely," with turbare, "to disorder."