As a child I one day noticed something funny at night. I saw a post office box lit up at one angle, but as I moved around it, the sheen and intensity of the shine changed. Obviously this was due to the refracting angle of the streetlight. It was interesting to me that the great circular glow in the middle at one angle, disappears at another angle. In other words, the glow isn't actually on the post office box at all, it's merely the point where the light bounced and my eye happened to catch it.
What I think is happening with these rays is that they do indeed start as straight lines emanating from the Sun, but when they hit the earth's atmosphere it becomes a focal point from which it will refract further.
Just like the double slit experiment, but at a large scale. The "slit" above is everywhere, and nowhere, it basically represents your current vantage point will give your vision access to seeing the rays that are splintering out from that angle. You move, it changes as well (but you don't notice because it's so minuscule)
