Why so much snot after recovering from a cold?

A cold, it seems, comes in two phases:

  1. The feverish, sore-throat, aching sinuses, incredibly nasty phase,
  2. and the juicy phase, characterized by copious quantities of snot and plentiful horkage of lung butter.

During phase 2, while I’m much less pleasent to be around, I’m always feeling pretty much fine. Fever’s gone, no more aches and pains. But I’m filling up a dumpster with used kleenexes.

So, why so much more leakage after the worst of a cold has passed? And at that point, am I still contagious?

While Cecil doesn’t tackle the phase issue, he does explain how copious snot gets produced: