Exploring Cloud Microphysics and Electric Fields in Non-Lightning Clouds over the Third Pole: First Results from a Tethered-Balloon Campaign

Cloud electrification plays a key role in lightning initiation and the atmospheric electric circuit, yet high-resolution in situ observations relating electrification to cloud microphysics, aerosols, and thermodynamic conditions remain scarce. Previous studies mainly focused on thunderclouds, very few campaign reveal such relations in non-lightning clouds. Here we present the first tethered-balloon campaign over the Tibetan Plateau (the Third Pole) to investigate aerosol–cloud–electric field interactions. The observations are complemented by ground-based instruments and satellite data to characterize electric fields, cloud properties, aerosols, and meteorological conditions. Multiple flight strategies, including vertical profiling, cloud-edge transects, and in-cloud hovering, were employed to resolve fine-scale processes. Five representative cloud cases were investigated with strict data quality control. Results show that cloud droplet size and liquid water content increase with height, consistent with condensational growth, while decreasing droplet number concentration indicates significant entrainment. Strong correlations (|r| > 0.78) between cloud-base aerosol number concentration and cloud microphysical properties confirm aerosol activation effects in the pristine plateau environment. Both the electric field strength and liquid water content are low in non-thunderstorm warm clouds. In-cloud electric field anomalies (±100 V m⁻¹) exhibit altitude-dependent variability but show no clear relationship with droplet number concentration or effective radius, suggesting relatively homogeneous charge distributions in the absence of active lightning discharges. Observations also reveal that the differences between in-cloud and out-of-cloud electric fields is considerably small. These results provide observational constraints on aerosol–cloud–electricity coupling over complex terrain and demonstrate the potential of tethered balloons for high-resolution cloud measurements.