I used to think that the sun glaring in my eyes was simply a function of its position in front of me. But sometimes, the weather or traffic report warns us about the glare, and that leads me to suspect that the glare is caused by a specific set of meteorological conditions. What might they be?
I’m not sure I have ever heard specific warnings for glare, but it could be down to:
a) wet road surface, which can reflect the sun and be very dazzling, or
b) The angle of the sun at the specific time of year and day, which can align with roads and ensure that it shines right in your eyes. (See Manhattanhenge.)
Another factor is the clarity of the air. Pollution does a great job of lessening glare.
You don’t typically look at the sun or anywhere near it, but a reflection from a polished surface can have 50-90% of the same strength. Having such reflections in your normal arc of vision can make it overpowering.