In the late 18th century, Count Rumford discovered the phenomenon of heat transfer in fluids—a process called convection—as he examined why some English desserts, such as apple pie, stay warm for so long. Convection as it pertains to atmospheric phenomena, however, is no pie-in-the-sky concept. Many clouds, including the puffy cumulus or more threatening cumulonimbus, get their start thanks to the rise of sun-warmed air and water vapor. Fortunately, scientists today have more tools at their disposal than in Rumford's day with which to study the characteristics of cloud evolution. The visualization below uses data from the NASA Goddard Cumulus Ensemble Model to simulate a thunderstorm that formed on February 23, 1999 in Rondonia, Brazil. Watch as clouds grow, rise, merge and give way to rain. The entire evolution typically lasts a few hours, but is accelerated in the video to be viewed in just under a minute.