Advanced dropsondes that could effectively be guided through atmospheric regions of interest such as volcanic plumes may enable unprecedented observations of important atmospheric phenomena. IDI proposes to develop a flight ready optical sensor to provide cloud properties and hazardous volcanic ash and icing information within commercial airspace. The probe will initially be developed for a dropsonde but eventually be integrated into the unmanned SCAN EAGLE UAV. The innovation is a new capability for making in-situ measurement of cloud particulates to improve pilot awareness of hazardous operating conditions, such as those recently experienced by aircraft engines operating near volcanic plumes in the North Atlantic near Iceland. . During a Phase I program IDI developed a miniature Nephelometer sensor prototype and demonstrated the ability to measure small ash and water particulates as well as provide discrimination between them. Phase II will integrate the Nephelometer and a commercial SO2 sensor into a radiosonde package for a tethered field test at the NASA Wallops test facility and finally deployed near an active volcano in central America. The probe packaging will designed such that it is upwardly compatible in size and weight with the SCAN EAGLE UAV payload as well as other payload recovery vehicles.