How do chimneys let smoke out but not snow in?
1.) When there is a fire in the fireplace, the heat creates an updraft and draws the smoke up the chimney. The updraft would keep snow and rain from going into the chimney. 2.) Many chimneys have a slight curve or bend in them where smoke can still escape but something falling straight down the chimney, like soot or rain, doesn’t have a direct straight path back to the fireplace. 3.) Many chimneys have a rain hood over the top. Sort of like a rigid umbrella. 4.) Snow doesn’t fall in enough quantity to put out a fire. You can make a campfire outside in the heaviest of snow falls and the snow still wouldn’t fall fast enough to put out the fire (assuming the wind isn’t so strong as to blow away the fire).
