Less precipitation and more lightning eventually may be forecast as a result of a NASA study that shows that cloud droplets freeze from the outside inward instead of the opposite. The new theory of how super-cooled water droplets in clouds freeze, which appears in this week’s on-line edition of the Proceedings of the National Academy of Sciences, reverses a 60-year-old assumption.
Physicists in Israel have developed a new formula for predicting when clouds will spew forth rain. The trick, it seems, is all in the cloud turbulence. The more turbulence, the greater likelihood small droplets will smack into each other and form larger, heavier drops that fall to earth. Clouds are formed by warm water vapors rising to the sky. When a cloud cools, the vapors condense into droplets that increase in size and are eventually pulled back to earth by gravity, causing rain. Simple as this cycle may sound, when and where exactly the rain will fall is extremely difficult to predict.