Aridity is an index value that attempts to combine average temperature and precipitation data into one value. It is computed by subtracting the precipitation departure from the temperature departure. The departure is measured in units of sigma (standard deviation), which allows for the two departure values to be combined as they have the same units. Increasing positive values indicate more water stress and negative values the opposite. The featured chart presents this metric computed for Ames over three different day intervals. This chart shows the "flash drought" nature of what Ames has recently experienced as a quick transition from less water stress to more water stress has happened over the past two months.

Voting:
Good = 11
Bad = 0