An unprecedented analysis of the atmosphere of planet Earth is currently underway with the involvement of over 140 countries in the Global Weather Experiment—the largest international scientific experiment yet attempted. After many years of planning, the Operational Year began in December of 1978. Following the field phase and data management phase, a multi-year evaluation and research program will commence and continue until the late 1980s. During this period, scientists and technicians will examine the atmosphere, the sea surface, and the upper layer of the world's oceans in the most intense survey and study ever made. A number of successes and failures occurred in preparing for the observing phase and these are mentioned as each observing system actually deployed in the field is reviewed. The focus of the paper is on the quantity of data gathered and how it was obtained. The article concludes with some suggestions for assurances of final success of the Experiment.