Relative Humidity Introduction Relative humidity is, perhaps, the most common measure of atmospheric moisture, especially among lay persons and on radio and television forecasts. The reason is probably because it seems easiest to understand at first glance. It describes how close the air is to being saturated. In this activity you will practice computing the relative humidity and inspect a weather product that uses it.
Objectives Be able to compute and interpret relative humidity.
The basic mathematical concept behind interpolation is that of ratios or fractions. They are 21.0 and 25.0 mb, respectively. The total distance from 21.0 to 25.0 is 4.0. Be sure that you understand the computation above and then study the following examples. To complete the calculations of relative humidity given the temperatures and dew points in the following table, you will need to use interpolation to obtain some of the vapor pressures.