## Flexi Says: The rate of evaporation is the mass or volume of water that evaporates from a unit surface area in unit time. It can be expressed as kilograms or liters of liquid water evaporated per unit area per day in a body of water, or in smaller units for a smaller container of water. This volume of water evaporated can be obtained by measuring the equivalent depth of water evaporated, and multiplying that by the surface area of the exposed water.