Can I add break times on individual days?

For example, On Wed Nov 13th I'll just be working in the morning. Normal hours are between 8am and 5pm, but on that day they are between 8am and noon. I COULD book fake appointments all afternoon to block any real appointments, but it seems like there must be an easier way. I have days like this frequently enough that I need to be able to block out a few hours at a time without affecting other days in my normal schedule. Thanks!