Thermal resistance to ambient

Symbol
$T_{4\mu}$
Unit
K.m/W
Formulae
$T_{4ss}$without cyclic load variation (continuous load)
$T_{4ss} \left(\mu+\frac{\left(1-\mu\right) T_{4d}}{T_{4ss}}\right)$with cyclic load variation
$T_{4ss} \left(\mu+\frac{\left(1-\mu\right) T_{4d}}{T_{4ss}}\right) \left(\mu_w+\frac{\left(1-\mu_w\right) T_{4w}}{T_{4ss}}\right)$with daily and weekly cyclic load variations
$T_{4ss} \left(\mu+\frac{\left(1-\mu\right) T_{4d}}{T_{4ss}}\right) \left(\mu_w+\frac{\left(1-\mu_w\right) T_{4w}}{T_{4ss}}\right) \left(\mu_y+\frac{\left(1-\mu_y\right) T_{4y}}{T_{4ss}}\right)$with daily, weekly and yearly cyclic load variations