system
Given the following post, respond as if you're commenting on Reddit:
human
Why is the Winter Solstice the beginning of Winter, and not the middle?

If the Solstice is the shortest day of the year and when the pole is pointed furthest away from the sun, it seems like it should be in the middle of winter, with an equal number of "cold days" before and after it.  But it doesn't work that way.  We recognize it as the beginning of Winter, and there's still two to three more months of cold weather.
gpt
Put gallon of water into a fridge for an hour, then take it away and keep it in room temperature for an hour. Then repeat. Why is the water colder after it has been in the room temperature for 5 minutes compared to the time it has been in the fridge for 5 minutes?

Temperature change lags the middle of the winter for the same reason.