Sometimes, under direct sunlight, clouds will appear gray or dark gray against a blue sky or larger backdrop of white clouds. There are usually two reasons for this effect.

Night sky photographer Ruslan Merzlyakov captured bright blue-white noctilucent clouds dancing over Nykøbing Mors in Denmark just before dawn on July 1.

According to Sarah Keith-Lucas from BBC Weather, "dust, pollution, water droplets, and cloud formations" can influence the colors of the sky, too.Occasionally, pink and purple will appear more ...

Night sky photographer Ruslan Merzlyakov captured bright blue-white noctilucent clouds dancing over Nykøbing Mors in Denmark just before dawn on July 1.