Dear Tom,
How much rain, on average, does the entire United states receive in a year? How about globally?
John Schewe, Naperville
Dear John,
The National Climatic Data Center (NCDC) pegs average annual precipitation in the contiguous 48 states at 30.21 inches. (Compare Chicago's annual total of 36.89 inches) This is liquid precipitation (rain and drizzle) plus the water content of frozen precipitation (such as snow, sleet and hail). In addition, NCDC indicates that the average snow-to-water ratio is 13:1 (13 inches of snow yields one inch of water). Estimates of average annual global precipitation range from 35 to 44 inches, but exhaustive studies by the Global Precipitation Climatology Project using satellite and radar data and data from more than 30,000 observation stations indicates a global average of 41.34 inches.
