In the water cycle, what physical process is primarily measured using an evaporometer or atmometer?

Correct answer: Rate of evaporation from an open water surface

Correct answer: B. Evaporation is the physical change in which liquid water at a surface gains enough energy to become water vapour. An evaporometer or atmometer is designed to estimate the rate of this water loss from an exposed or open surface under particular atmospheric conditions. The reading is influenced by factors such as temperature, wind movement, humidity, and available energy. A is different because transpiration is water loss through plant tissues, especially leaf stomata; it may be studied with other methods or instruments. C is the entry of water into soil and is measured through infiltration studies, not with an evaporometer. D concerns atmospheric motion rather than a water-phase change. Although some atmometers may use a porous surface to represent evaporative demand, the physical process being assessed is evaporation or atmospheric evaporative demand, not rainfall or infiltration. Memory cue: “evapo-meter” measures evaporation; “transpiration” belongs to living plants.