What do the grant and kettlewell experiments show with regards to evolution?

Kettlewell's experiment was a biological experiment in the mid-1950s to study the evolutionary mechanism of industrial melanism in the peppered moth (Biston betularia). ... The experiment found that birds selectively prey on peppered moths depending on their body colour in relation to their environmental background.

answer: ice crystals in air

the water from the water body or another source of water gets evaporated as water vapor as an effect of heat on water. these water vapor rises in the upper layers of the earth atmosphere under high atmospheric pressure. the atmospheric pressure of these water molecules starts to decrease due to the effect of cold air. the invisible water vapor condenses into visible water droplets and ice crystals.these ice crystals and water droplets being less denser than the surrounding air floats on air as clouds.