a layer of water in an ocean or certain lakes, where the temperature gradient is greater than that of the warmer layer above and the colder layer below.
As definitions go, that one sucks.
A thermocline (also known as the thermal layer or the metalimnion in lakes) is a thin but distinct layer in a large body of fluid (e.g. water, such as an ocean or lake, or air, such as an atmosphere) in which temperature changes more rapidly with depth than it does in the layers above or below. In the ocean, the thermocline divides the upper mixed layer from the calm deep water below. Depending largely on season, latitude and turbulent mixing by wind, thermoclines may be a semi-permanent feature of the body of water in which they occur or they may form temporarily in response to phenomena such as the radiative heating/cooling of surface water during the day/night. Factors that affect the depth and thickness of a thermocline include seasonal weather variations, latitude and local environmental conditions, such as tides and currents
Maybe not what I’m going for.
The J-man gifted me the most awesome birthday present. An instant infrared thermometer! It’s like the most gadgety gadget I have ever had! Temperature of the mail box at 8:30? Exhaust coming from dryer vent in garage? Computer screen? Inside of Missy’s ear? These are all now matters of fact and not speculation.