system
Given the following post, respond as if you're commenting on Reddit:
human
When your car windows fogs up on the inside during cold weather, is it better to use hot hair or cold air to clear it up?
gpt
**Cold air for the short run, hot air for the long run.**

This is what happens:

- before you get into the car, the air both inside and outside of the car is cold (cold air can't hold much moisture)
- when you get into the car, the air temperature in the car is raised   breathing adds moisture to the air, which condenses on the window - think condensation of a cold beer bottle on a hot day

*If you turn on the air conditioner* you'll eliminate condensation by having both sides of the window at the same temperature. Corollary: keep the aircon on, otherwise the window will fog up again because of the temperature difference.

*If you turn on the heating* you'll add capacity to the air to absorb moisture (warm air has a larger capacity, think humid summer days vs. dry winter days), thus removing it from the window. This process will take a bit longer between heating up the air and transferring all the vapour away from the window, but it will be more sustainable, and, more imporatantly, more comfortable.

**tl;dr: turn on the heating and be patient.**