Nimbus

The nimbus is a microscopic bacteria which floats amongst the clouds. It has developed many feathery fronds which lift it into the air. It is transparent and absorbs ultraviolet light for photosynthesis. It can last for a long time without water or even air. But when it comes in contact with moist air such as clouds it will being reproducing. Those that get blown high into the upper atmosphere can stay dormant in the cold airless space and those that fall to the ground usually die or are eaten by other microbes.