Clouds and silver lining
I know the expression "every cloud has a silver lining". I know its meaning, I know its origin, I know the meaning of individual words.
What I do not understand and failed to find an explanation for, is why would someone starts talking about a lining inside clouds. I assume the silver part is merely an analogy to the grey color of the clouds, yet if it is a lining, there is no reason for it to be visible on the outside. But what about the lining? In my understanding as well as the dictionary's (M.W.) a lining is what covers the inside of something.
How does that apply to clouds? Is it like pretending clouds are hollow? Is this about a sort of imaginary hidden treasure? I know the expression is not about a real physical lining, let alone silver made. But still, does a native English speaker understand easily how a cloud could have a lining or is the expression just taken as it is, without trying to parse it? Could someone please tell me what I am missing?
Stating the obvious, English is not my mother tongue.
Reply regarding an alleged duplication: my question is strictly about the possibility of a literal meaning to the expression, not its origin in a regular sense. I made it clear I knew both the origin story (Milton) and meaning (bright side).
Solution 1:
As requested by the OP I am converting a comment without references to an answer.
The real world effect you are missing is the sun or moon shining on the edge of a dark storm cloud giving it a partial bright rim. I don't know about other parts of the world but this is quite common in Britain where the metaphor originates. @Xanne gave This Link showing that the idiom is credited to John Milton who was a 17th century poet. To a 17th century eye this could look like the lining of a cloak showing at the edge of the dark outer material: if such a cloak were to be turned inside out the entire lining would show almost hiding the main fabric. The metaphor means that, although things may look gloomy, you can 'look on the bright side' and see the positives.
There is a song written by Ivor Novello and Lena Guilbert Ford in 1914 called Keep The Home Fires Burning which has a refrain containing the lines
There's a silver lining
Through the dark clouds shining,
Turn the dark cloud inside out
Till the boys come home.
(Note the idea of 'turning the dark cloud inside out' like a cloak used 300 years after Milton. Some images persist in the imagination.)
This was very popular during the First World War and had a second bout of popularity during the Second World War.
More recently and more irreverently Eric Idle of the Monty Python team created "Always Look on the Bright Side of Life" for the film "The Life of Brian" which references the idea of things having a dark and light side to them. Not quite 'turning the cloud inside out' but very similar. Don't forget that Eric Idle was born during WW2 and would have been very familiar with "Keep the Home Fires Burning" as a child in the late forties and early fifties, possibly to the extent of being sick of it!
Solution 2:
Actually the lining pertains to the bright border of the clouds on a bright day.