The sky is always there, regardless rain or shine; good or bad.
Cloud comes in different sizes and shapes. Like randomness, impermanence in the world. Also reminds one of different people, characters of all kinds.
People may think grey cloud is bad, because it implies incoming rain. But rain fills up reservoir and provides water to fishes in rivers. A person may look haggard and older than his/her age, perhaps because he/she worked hard to support family.
Grey cloud implies incoming rain. Later it rain, even though the weather forecast says no rain. Don't trust forecast 100%. The forecast may be inaccurate or too general to be applicable to your situation.
Sky does not judge. It does not care whether there's cloud or blue sky, rain or shine. We may need to exercise judgement in our work, our life. Should we be like the sky when there's no need to judge?
Post-note: Sky reminds me of a Chinese saying: 天有不测风云，人有旦夕祸福 (source)
