Precipitation-evaporation ratio
From Glossary of Meteorology
precipitation–evaporation ratio
(Abbreviated P–E ratio;
also called precipitation-effectiveness ratio.) For a given locality and month, an empirical expression devised for the purpose of classifying climates numerically on the basis of precipitation and evaporation: where P is the normal monthly precipitation in inches and T the normal monthly temperature in degrees Fahrenheit. All temperatures below 28.4°F are given the value of 28.4°, and P–E ratios greater than 40 are counted as 40.
also called precipitation-effectiveness ratio.) For a given locality and month, an empirical expression devised for the purpose of classifying climates numerically on the basis of precipitation and evaporation: