Is it normal for my dog to bark at nothing?

My dog barks every single morning at the wall for hours. She’s a huge dog and her bark is extremely loud. Everytime I try to bring her inside when she barks, my mom gets mad and says that that’s what dogs do and that I’m not the normal one because I wake up late. (It’s literally 8am) I’ve told my mom to put her in the other side of the yard where she doesn’t bark and she says no it’s normal for dogs to be free to bark!!

My neighbors live really close to us and they have children so I feel really bad.