In story when cloud has silver shine that mean hope and beauty in sad dark time, cloud look dark by morning but sun rays make it silver like money glow, this show even in sad moment there is light and chance.

Also silver shine cloud can mean imagination and dream, maybe character think of future bright time, so author use this image to give feel of hope and better day coming

No need special, simple picture in mind cloud shine silver, it lift mood and inspire person in story, this is meaning of silver cloud there.