Rate of Geothermal Temperature T_G({\bf r}) change along True Vertical Direction:
(1) | G_T({\bf r}) = \frac{\partial T_G}{\partial z} |
Fig. 1. Schematic view of the Earth's Geothermal Temperature Gradient. |
The common agreement is that
(1) does not account effects of the seasonal/daily temperature variations ( which are only noticeable above Neutral Temperature Layer ).
The most common value of Geothermal Temperature Gradient away from tectonic plate boundaries : GT = 0.025 ÷ 0.030 °C/m.