To divide one power of ten by another, simply subtract the two exponents (see Multiplication/Division). Next, convert the two numbers from scientific notation to real numbers. Now add the two numbers normally. Finally convert to scientific notation if the coefficient is less than 1 or greater than 10.
Precipitation occurs when cloud droplets combine and grow large enough to fall to the earth the rate of evaporation as a drop falls to the earth also can affect its size. from: sadia aisa.
Either the cloud will dissipate and the water droplets will become vapor again, or the cloud will grow and it will begin to precipitate. The third and final step of the water cycle is precipitation. Precipitation includes all water that falls from the sky, both in liquid and frozen form, which reaches the ground.