The primary factor accounting for the lack of sounding data availability is, quite simply, cost. Budgets allocated to soundings in developing countries of Africa and South America are often limited or a minute part of a bigger budget. This results in the inability of a vast majority of developing countries to comply with the standards set by the WMO in their 2007 revision of the WMO Convention originally published on 11 October 1947. Here, we take as an example the Instituto de Hidrologia, Meteorologia y Estudios Ambientales (IDEAM), which, as the governmental institute for meteorological and hydrological services of Colombia, is responsible for recording the climate at a national level. In 2011, the meteorological station of the IDEAM in Leticia (WMO #80398), based in the southern tip of the Colombian Amazon and hence in charge of recording meteorological data on global water vapor regulation in a critical region, received funding for a total of only 119 flights, whereas the T HE IMPORTANCE OF ATMOSPHERIC SOUNDINGS. While accuracy and coverage of satellite imagery have improved markedly in recent years, radiosonde-collected data still provide us with the most detailed measurements of the troposphere (i.e., the lower part of the atmosphere where most hydrological atmospheric processes occur) due to their fine vertical resolution (i.e., 5-10 m). However, instrument biases (temperature, relative humidity, pressure, wind direction, and wind speed) are compounded in the tropics by relying on sparse sampling of data. Figure 1 shows the locations of operational sounding stations from the Global Climate Observing System (GCOS) upper-air network (GUAN) as recorded by the World Meteorological Organization (WMO) in February 2011. The figure illustrates the scarcity of sounding stations, particularly in developing countries compared to other parts of the globe.