Thus there is convection within the troposphere that (to a first approximation) tends to sustain some lapse rate profile within the layer — that itself can vary as a function of climate (and height,
location, time), but
given any relative temperature distribution within the layer (including horizontal and temporal variations and relationship to variable CSD contributors (water
vapor, clouds)-RRB-, the temperature of the whole layer must shift to balance radiative fluxes into and out of the layer (
in the global time averae, and
in the approximation of zero global time average convection above the troposphere), producing a PRt2 (
in the global time average) equal to RFt2.