Good stuff!
OK- the bit about cooling EGT makes sense- lower temp, higher density (all other factors being equal). And we've all observed a temperature drop entering a cloud.
As to the updraught, there might well be something in it, however, I think I've noticed the effect on stratoform type clouds as well.
So, in summary- the density of the air in the cloud is relatively high, due to the temperature difference.
Anything else to add, or is that a complete solution? I'm not sure!
CC