Clouds are made of tiny water droplets and ice. The water droplets are tiny that they cant float in the air.
The air contains gas but are in the form of invisible gas when close to the earth ( water vapour).
Warm air expands and cool when it rises but cool air can not hold as much water. Some of the vapour condenses into tiny pieces of dust floating in the air to form tiny water droplets around the dust particles.
These droplets come together to form a visible cloud.
In low light no plants grow. With no plants no animals can eat so less animals remain or stay there. With less animals less animals respire and breathe out CO2.
