system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does the top post on the front page seem to appear out of nowhere when all the other posts on the front page stay in roughly the same position?
gpt
Due to the time aspect of the algorithm, a post reaches 1, then slowly will move down (if it follows a similar ratio of up/down votes (likely), as opposed to dropping out of sight if there was a backlash of downvotes on it)

But a new post would be upvoted at its own ratio which will often be higher than other posts on the front page, and therefore quickly reach the top position since it is newer and has higher upvote ratio than everything else currently on the front page (due to previous high upvote ratio posts are likely ranked lower due to age by this time)