A laboratory study of the electrostatic charge of individual sand particles lofted in an electric field

Laboratory experiments are developed to measure the electrostatic charge of individual particles lofted into air by electrostatic forces. By tracking the magnitude of charges on the sand particles as they move, it can be inferred that no discharge occurs within a full trajectory. The distribution of particle charge is related to particle size, as well as conditions such as the electric field and relative humidity. We now show that our experimental results for particle charge can be accurately predicted by theory without any fitting parameters. The excellent agreement between theory and experiment shows that the experimental methodology developed here is accurate. Furthermore, the results provide direct evidence for the previously proposed idea that sand particles lofted in an electric field behave like conducting particles, due to conducting water layers that arise from ambient humidity, and gain their charge by induction in an electric field. This electrostatic process will occur in natural sand and dust storms, and the enhanced dust loading will have atmospheric and climate implications.