This project involves investigating use of an electric field radiosonde (Electrosonde) carried aloft by a weather balloon to measure the potential of the ionosphere, which the PI postulates is controlled by tropical temperature. Such data may provide a new way to monitor global temperature and test numerical models. Each single measurement provides a proxy index of the integrated temperature and convective activity over the Earth at tropical latitudes, the region which controls global temperature, the general circulation, and various other global aspects of the weather. Another advantage of this technique is that a naturally occurring phenomenon is being observed - integrated deep tropical convection - vs. existing methods for observing "global warming" involving thousands of temperature measurements with associated uncertainties. The results of the Phase I effort were that a reliable electric field instrument was developed and 31 V1 soundings were obtained. The temperature - V1 relationship was significant at the 99% confidence level. In Phase II, 3 widely separated stations will be used for simultaneous measurements and to sample different air masses. The measurement of air conductivity will be added to the electrosonde to detect aerosols and radioactive material, each of which can affect the global atmosphere.