6. Which of the following best describes the theory of punctuated equilibrium?
a. Biological change occurs quickly over a short period of time.
b. Tiny changes in a species add up to major changes over time.
C. A biological change occurs slowly and steadily over a long period of time.
d. Events throughout the history of life have caused the extinction of species.

the correct answer is d

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.