Beyoncé rang the alarm on the Fourth of July with the release of her first new song in two years. The superstar musician dropped “Morning Dew (Donk),” which she wrote with Pharrell Williams, The-Dream and Darius Dixon and produced with Williams, on Saturday morning. The track, set to be included on the 20th anniversary edition of her sophomore album B’Day, starts a 60-day countdown to that reissue and her next birthday on Sept. 4. B’Day was first released on Beyoncé’s 25th birthday, Sept. 4, 2006. It was her second No. 1 album, which sold more than 541,000 copies in its first week of release and includes hits like “Irreplaceable” and “Ring the Alarm.” “Morning Dew” was released with a black-and-white lyric video featuring old footage directed by Cliff Watts, who shot Beyoncé’s Sports Illustrated Swimsuit cover in 2007. The track is a “special gift to her fans,” and “is a direct nod to her loyal BeyHive,” a release from Beyoncé’s Parkwood Entertainment says. “Morning Dew” is Beyoncé’s first new song since she released her Cowboy …