During pregnancy, felicia has been extra careful to avoid foods that could potentially cause food-borne illness. even though she loves the greek salad at her favorite restaurant, the waiter could not confirm whether or not the feta cheese on the salad was pasteurized. why should pregnant women avoid unpasteurized cheese?

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.