|MadSci Network: Astronomy|
I'm afraid your dad's right. At the Equator, the Sun moves more or less perpendicular to the horizon. However, as you move towards the Poles, the Earth's tilt means that the Sun's path across the sky tends to be at an angle to the horizon. In fact, at either of the Poles, the Sun moves parallel to the horizon and takes months to rise and set.
Take a look at this answer from our archives for more information.
Jim O'Donnell, email@example.com
Try the links in the MadSci Library for more information on Astronomy.