Well, things don't quite match that neat picture.
In the days before December 22, the sun actually does rise slightly later every day. But it also sets slightly later every day, though the daily increments are smaller than with the sunrise. The result: the days get progressively shorter.
In the days after December 22, the sun continues to rise slightly later every day. It also sets later every day, though now the daily increments are larger than with the sunrise. The result: the days start to lengthen, just as expected.
And this trend continues till … today, January 14. It is only after today that the sun starts rising slightly earlier every day.
Questions: Is this why January 14 is a marked day on Indian calendars (Pongal, or Sankranth)? And is this date a function of the earth's latitude? Or of its tilt on its axis? Or something else? In other words, can you explain this phenomenon to me in terms I can understand?
PostscriptThere should be a similar, but mirror-imaged, phenomenon around the summer solstice, June 22. Is July 14/15 a similarly marked date anywhere?