单词手册上的例句：the skies above london were ablaze with the spectac

表示天气,和正常的复数概念用skies
稍微拽一拽（flowery,poetic,literary,portentous,decorative）也可以用skies.（我认为本句中如此）
Oxford:You usually say the sky.When sky is used with an adjective,use a… sky.You can also use the plural form skies,especially when you are thinking about the great extent of the sky
正常用sky,形容词加在冠词与sky之间.
可用复数,特别是表示广袤、宽广的大片天空.