For cables in tunnels, this is the temperature of the air at the inlet.

For cables in troughs, this is the temperature of the air inside the trough of the previous iteration cycle. It is initially equal to the ambient air temperature above ground.

Symbol
$\theta_{\mathrm{at_{\mathrm{0}}}}$
Unit
°C
Used in
$\Delta \theta_{\mathrm{0t}}$
$\theta_{\mathrm{at}}$
$\theta_{\mathrm{at_{\mathrm{L}}}}$
$\theta_{\mathrm{at_{\mathrm{z}}}}$