Please use this illustration with the associated copyright information. The National Drought Mitigation Center commissioned the artwork in the late 1990s to show how drought, as a slow-moving natural disaster, tends to emerge under the radar screen, and then intensify until people can no longer ignore it or wish it away. When drought ends, people are often glad to forget about it and to resume business as usual. Although people need to appreciate the return to normal, they also need to stop and learn from their experiences. Climatology shows that drought will happen again. What can people learn from one drought that will ease the pain of the next?
The NDMC's illustration of the hydroillogical cycle builds on earlier observations of human perception. I.R. Tannehill noted in Drought: Its Causes and Effects in 1947:
We welcome the first clear day after a rainy spell. Rainless days continue for a time and we are pleased to have a long spell of such fine weather. It keeps on and we are a little worried. A few days more and we are really in trouble. The first rainless day in a spell of fine weather contributes as much to the drought as the last, but no one knows how serious it will be until the last dry day is gone and the rains have come again.