The neurology of a person with autism does not automatically organize the world outside their skin. When we are able to organize the happenings in the world we usually do so differently than neuro majority people.
As a young child I saw over and over how light from the sun interacted with water particles rising from the ground and with water droplets in the air. This repeated experience became useful over time in that I learned the predictability of this occurrence. I also learned the effects of various factors (such as clouds, rain, air temperature, wind, etc.) had on impacting the interaction of sun brightness with air and ground moisture.