I think a lot of it has to do with the amount of moisture (humidity) in the air being less when when the temperature drops. The moisture is unable to be picked up and carried from the air by the PG or VG as it "normally" is.
I know right now here in my location its -29C and very difficult to tell if I'm seeing vapor or just the normal winter breeath exhale. In my home my humidity is waay down to 22% and again my exhaled vapor is more thin than usual compared to when its at 32-35%.
And yes.... out in the cold my
batteries certainly don't last as long at all.
VapeOn,
Greg