Winter solstice is an astronomical phenomenon marking the shortest day and the longest night of the year.
In the Northern Hemisphere, the December Solstice is the Winter Solstice.
Although winter is the season of dormancy, darkness and cold, the December Solstice marks the "turning of the Sun" and the days slowly get longer.
Celebrations of the lighter days to come and nature’s continuing cycle have been common thorughout cultures and history with feasts, festivals and holidays around the December Solstice.
Reference: http://www.timeanddate.com/calendar/december-solstice-customs.html
At the Cliffs of Moher it's sunrise at 08:45 and sunset at 16:22.