Question

this is the area of sudden change in temperature in water. thermocline pycnocline halocline surface tension

Explanation:

A thermocline is a layer in a body of water where there is a sudden change in temperature. A pycnocline is a layer where there is a rapid change in density. A halocline is a layer where there is a sudden change in salinity. Surface - tension is the property of the surface of a liquid that allows it to resist an external force. The description in the question matches the definition of a thermocline.

Answer:

Thermocline