Why do particle clouds generate electric charges?

Particle-size dependent bipolar charging of Martian regolith simulant

(2009) Keith M. Forward et al.   GEOPHYSICAL RESEARCH LETTERS

Non-coalescence of oppositely charged drops

(2009) W. D. Ristenpart et al.   NATURE

Electrification of granular systems of identical insulators

(2009) Jasper F. Kok et al.   PHYSICAL REVIEW E

Enhancement in wind-driven sand transport by electric fields

(2009) Keld R. Rasmussen et al.   PLANETARY AND SPACE SCIENCE

Electrostatic Charging Due to Separation of Ions at Interfaces: Contact Electrification of Ionic Electrets

(2008) Logan S. McCarty et al.   ANGEWANDTE CHEMIE-INTERNATIONAL EDITION

Spontaneous tribocharging of similar materials

(2008) T. Shinbrot et al.   EPL