If we can’t see air, can fish see water ?

The adaptive system plays a role here. Fish can’t see water because their optical speed of the velocity of what they see is limited. We as humans can’t see air because the air consists of particles that are to difficult for us to see with our evolved retinas to distinguish.

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.