system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is the shortest day of the year (solstice) the first day of winter and not the middle of winter?

Logically it seems like it should be the middle. Days have been getting slowly shorter and colder, then after the solstice they start to get longer again, so shouldn't they also be getting warmer?
gpt
The coldest parts of winter don't coincide with the shortest days. The ground and the oceans actually hold onto the heat from summer pretty well, so the coldest bits of winter don't happen for awhile.