Which term denotes the middle layer where temperature drops rapidly?

Which term denotes the middle layer where temperature drops rapidly?

• A. Epilimnion
• B. Thermocline
• C. Metalimnion
• D. Hypolimnion

Answer: (C)

In stratified lakes you have three main vertical zones: a warm, well-mixed surface layer; a middle transition zone where temperature changes rapidly with depth; and a cold bottom layer. The term that denotes this middle layer is metalimnion. It names the depth interval between the warm epilimnion above and the cold hypolimnion below, where you observe a noticeable drop in temperature as you go deeper. Within this layer lies the thermocline—the region of the steepest temperature gradient—but the layer itself is the metalimnion. The epilimnion is the surface layer, and the hypolimnion is the bottom layer, so they don’t describe the middle zone.

In stratified lakes you have three main vertical zones: a warm, well-mixed surface layer; a middle transition zone where temperature changes rapidly with depth; and a cold bottom layer. The term that denotes this middle layer is metalimnion. It names the depth interval between the warm epilimnion above and the cold hypolimnion below, where you observe a noticeable drop in temperature as you go deeper. Within this layer lies the thermocline—the region of the steepest temperature gradient—but the layer itself is the metalimnion. The epilimnion is the surface layer, and the hypolimnion is the bottom layer, so they don’t describe the middle zone.