t is the number of hours elapsed since the begining right?
but we dont know when it began... we only now what has happened between 6ama nd 8am, so we designated T hours to have passed between the beginning of the snow falling (which we dont know - we want to find out) to 6am, and once we find T, we simply subtract from 6am to get when it started
T becomes our reference point cause we know 8 am is T+2, and 3.5 hours after that is T+5.5, etc
