Why do biologists consider procaryotes important? (more than one answer can be correct.)
a. they constitute most of the biomass on earth
b. they perform essential transformations of materials on which all other life depends
c. they are biochemically far less diverse than eucaryotes
d. they are the most numerous organisms on earth

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.

layer 3 is younger than layer 6.