The second part of the answer would happen whether there is sun or not. If it were a puddle instead of snow, we would easily jump to the conclusion that the water would disappear through evaporation into water vapor. Ice and snow also changes to water vapor, a process which is called sublimation. Wind can speed up the process of evaporation and sublimation and that early March day was not only cold, but quite windy.
Joe & Marie
Now the interesting question that comes to mind is what would happen if the distance scheme was changed so that we were closer in July rather than January while the angle of the Earth’s tilt stayed the same. In that case, our seasons would be the same, but our summers would be slightly hotter and winters slightly colder. Interestingly, the shape of the Earth’s orbit and the tilt of the Earth’s axis do change, but over the span of tens of thousands of years, so you don’t have to worry too much.