1585OCTOBER 2004AMERICAN METEOROLOGICAL SOCIETY |

C louds are the most familiar aspect of our atmo-spheric environment. Schoolchildren around theworld learn the names of the different cloud types, names that were devised just over 200 yr ago by the amateur meteorologist, Luke Howard. Clouds take their names—cirrus, cumulus, and stratus—from Latin terms that describe the way clouds appear to someone standing on the ground. Cirrus clouds re-semble curls of hair, cumulus clouds look like piled-up heaps, and stratus clouds are spread out like blan-kets. While individual clouds may take innumerable forms, Howard’s system works because the shape of clouds is not completely random, but is instead gov-erned by some organizational principle. Because clouds also play a significant role in de-termining the radiation budget of the planet and serve as an important link in the hydrological cycle, they are studied using a variety of ground-based and sat-ellite techniques. Ground-based observers often use Howard’s cloud classification system, but clouds look very different when viewed from space. This is be-cause satellites are able to see, much more easily than a single observer on the ground, the range of scales at which clouds occur within the atmosphere. The scale of satellite observations falls within the mesoscale, defined by Orlanski (1975), to range from a few to a few thousand kilometers. Cloud organiza-tion at the mesoscale comes about because clouds act as tracers of vertical motion within the atmosphere, which is primarily due to convection. Depending on the strength of the vertical motion, convection can be deep or shallow. Deep convection extends through the depth of the troposphere and includes mesoscale con-vective systems and hurricanes. Shallow convection is much weaker and typically occurs within the low-est few kilometers of the atmosphere. While deep con-vective systems have been extensively studied due to their impact on human life and property, shallow con