Hi, everybody!<br/><br/>I have a question about "sky"<br/><br/>I see a lyric says, "You make me happy, when <u><b>skies</b></u> are grey."<br/><br/>"Sky" is uncountable. But I don't understand why "skies" here have to use in plural form? Can anyone explain to me?<br/><br/>Thank you!