The coldest nights are, well, nights, when the sun does not shine.

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To that end, green fuels require back-up generation that kicks in when the wind dies down or the sun ceases to shine.

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"When it looks like the sun isn't going to shine anymore, God put a rainbow in the clouds, " sung the 74-year-old, hosted onto the stage by Rastafarian poet Benjamin Zephaniah.

BBC: Angelou's rainbow of poetry

With most major economies in East Asia suffering their deepest recessions since World War II, brave is the forecaster willing to say just when the sun will come out -- and how strongly it will shine.

CNN: THE LONG, HARD CLIMB BACK UP