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.
Precipitation is moisture falling to the ground in the form of rain, snow or ice. Mountains have two major effects called the orographic effect, which causes clouds and precipitation to form on one side of the mountain, and the rain shadow effect, which is a drier area on the opposite side of the mountain.