A source of carbon... * -is anything that puts CO2 into the atmosphere
-is anything that takes up CO2 from the atmosphere and locks it away
photosynthesis
-fossil fuels which are buried deep in the ground

what's the question ?

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.