how does a water that you poured into a filter represent the concept of turbidity in nature?
It doesn't.. in fact it's almost the opposite. Turbidity is a measure of the degree to which water looses it’s transparency due to the presence of suspended particulates.
The more total suspended solids in the water, the murkier it seems and the higher the turbidity.
A filter obviously cancells all of that out because a filter process is to make it so that you have quality turbidity-less water.