Long time SBIR from soon after founding of the firm, Yankee Environmental Systems (YES) Inc was (in 2017) awarded a Navy Phase II supplement of almost $2M on a project initaited several years earlier. The firm is structured arounddeelopment of commercial instrumentation for both operational meteorology and research, providing instrumentation products to help solve difficult challenges involving temperature and moisture, atmospheric radiation and remote automated weather observation. Initially, efforts focused on problems affecting the global population such as acid rain, ozone depletion, air pollution, and global warming, subsequently these research areas have expanded to operational meteorology and homeland defense applications, such as tracking winds that may carry a plume from a dirty bomb. Yankee introduced the world's first no-moving-parts precipitation sensor based on hotplate technology licensed from the National Center for Atmospheric Research. The firm also offers internet-enabled data collection and storage approaches used in the line of Automated Radiosonde Launchers, Rotating Shadowband Spectroradiometers and Total Sky Imagers are just a few examples of the future of remote weather observation systems. YES optical humidity and water vapor instruments can be used in a wide range of process control and industrial dew point measurement. YES develops and manufactures scientific grade environmental sensing systems for measuring upper air, cloud cover, precipitation, temperature and humidity. The firm's expertise is in RF, UV/visible/IR electroptical radiometry and imaging, and embedded systems. Special Equipment/Materials: The High Definition Sounding System is a NASA WB-57F payload that dispenses up to 84 Model XDD-938 dropwindsondes from altitudes up to 62,000'. YES owns and operates this payload for NASA JSC customers to acquire winds, pressure/temperature/humidity and sea surface temperatures. The firm's engineering team is equipped to develop similar in-situ and remote sensing instrumentation such as microwave radiometers, radar and Doppler lidar