‟Clarity in Climate Modeling,” published in the November–December 2014 issue of American Scientist, chronicles my quixotic endeavour to understand how computer models of the Earth’s climate really work, from the inside out. Many of those models are huge software systems, not to be mastered by an dabbler on summer vacation. But smaller-scale models also offer genuine insight into the workings of the climate system. You can run them yourself. I even wrote one myself. —Brian Hayes