Not all of the specific energy consumed when evaporating water into the atmosphere (<i>&lambda;</i>) is due to the latent heat of vaporization (<i>L</i>). What <i>L</i> represents is the specific energy necessary to overcome affinities among liquid water molecules, neglecting the specific work done against atmospheric pressure (<i>p</i>) when water expands in volume (<i>V</i>) from liquid to gas (pV work). Here, in the one-dimensional context typifying micrometeorology, the pV work done in such an expansion is derived based on the Stefan flow velocity at the surface boundary, yielding a simple function of the virtual temperature; additionally, an empirical formula is provided that approximates <i>&lambda;</i> quite accurately over a useful range of environmental conditions. Neglect of this pV work term has caused a systematic 3&ndash;4&thinsp;% underestimation of <i>&lambda;</i>, and to some extent inhibited closure of the surface energy balance.
Kowalski, A. S. (2018). Technical note: rectifying systematic underestimation of the specific energy required to evaporate water into the atmosphere. Hydrology and Earth System Sciences Discussions, 1–4. https://doi.org/10.5194/hess-2018-195