Ameasure of the degree to which the water loses its transparency and becomes cloudy or hazy (similar to smoke in the air) due to the presence of suspended particulates.

Turbidity. As your book/question states it is a measurement of cloudiness in water.

consider an orange peel: if you want to try and lay it flat, you have to stretch it, we know exactly how things are being stretched or squashed at any given point. we have many different map projections because each has different patterns of some projections can even preserve certain features of the earth without