Idiom/Saying Explanation

Every cloud has a silver lining.

For example:-

When he lost his job he realised it really hadn't been what he wanted to do, so he retrained as a therapist. You see, every cloud has a silver lining.

You can usually find something good in negative situations.

It's raining cats and dogs! 

For example:-

"We had to run for shelter when it started raining cats and dogs."

It's raining very heavily.

Red sky at night, shepherd's delight.
Red sky in morning, shepherd's warning.

If the sky is red in the evening, at sunset, the weather should be nice the next day.
If the sky is red in the morning, at sunrise, the weather will be bad.

To look as black as thunder.

For example:-

"When I told them I was leaving, they looked as black as thunder."

To look really angry.

An ill wind.

( It's an ill wind (that blows nobody any good).)

For example:-

"The economic downturn meant there was a reduction in pollution. It's an ill wind."

Most events, no matter how bad, benefit somebody.