Hey everyone, sorry I've been so quite ( A lot is going on irl at the moment)
Anyway I decided to create a TIL on why your nose runs when it's cold outside.
Firstly we need to understand that an average persons nose creates just under a liter of mucus a day. Mostly all of it gets passed back into your throat and swallowed (Delicious i know).
So now when the outside air is cold your mucus production is increased significantly and thus some of it comes out the front
source
Why does this happen you ask?
Well let me explain, when it's cold outside the blood supply to your nose increases to warm up your nose itself as well as the cold air you are breathing in. Unfortunately the increased blood flow to your nose also increases the mucus created from the glands in your nose therefor creating so much it starts to flow down the front of your face.
Leaving a cold area will allow the blood to flow to the rest of your body and the blood flow will decrease in your nose. Your mucus glands will begin to produce mucus at the same rate as before and all will be well once again.
I Hope you taught you something today, if you enjoyed my post please follow me 
Steem on everyone!