  We present broad-band infrared photometry for 52 late-type supergiants in the
young Magellanic Clouds clusters NGC 330, NGC 1818, NGC 2004 and NGC 2100.
Standard models are seen to differ in the temperature they predict for the red
supergiant population on the order of 300K. It appears that these differences
most probably due to the calibration of the mixing-length parameter,
$\alpha_{P}$, in the outermost layers of the stellar envelope. Due to the
apparent model dependent nature of $\alpha_{P}$ we do not quantitatively
compare $\alpha_{P}$ between models. Qualitatively, we find that $\alpha_{P}$
decreases with increased stellar mass within standard models. We do not find
evidence for a metallicity dependence of $\alpha_{P}$.

Astrophysics