You wait for the muezzin to call out "Rama-dama-ding-dong" from the minaret.
But that is just a guess. I am not an Islamic scholar.
(, Tue 21 Jun 2016, 14:58, Reply)
www.theatlantic.com/international/archive/2013/07/how-to-fast-for-ramadan-in-the-arctic-where-the-sun-doesnt-set/277834/
(, Tue 21 Jun 2016, 15:00, Reply)
gave them rules to follow, then made these rules impossible to follow on various parts of the planet he created.
(, Wed 22 Jun 2016, 9:54, Reply)