This is the mean temperature of the medium filling the space between cable and duct.

Symbol
$\theta_{\mathrm{dm}}$
Unit
°C
Formulae
$\frac{\theta_{\mathrm{di}}}{2} + \frac{\theta_{\mathrm{e}}}{2}$
Related
$\theta_{\mathrm{di}}$
$\theta_{\mathrm{e}}$
Used in
$T_{\mathrm{4i}}$