Atmospheric charge separation mechanism due to gas release from the crust before an earthquake

In fair weather, the vertical atmospheric electric field is oriented downward (positive in the earth surface ordinate system) in the global atmospheric circuit. Some researchers revealed the unique phenomenon whereby once an upward vertical atmospheric electric field is observed in fair weather, an earthquake follows within 2-48 hours regardless of the earthquake magnitude. However, the mechanism has not been explained with a suitable physical model. In this paper, a physical model is presented considering four types of forces acting on charged particles in air. It is demonstrated that the heavier positive ions and lighter negative ions are rapidly separated. Finally, a reversed fair weather electrostatic field is formed by the above charge separation process. The simulation results have instructive significance for future observations and hazard predictions and it still needs further research.