Lightning in volcanic ash
If a volcanic eruption is not impressive enough already, try seeing it when lightning is involved. Normally ash and dust are electrically neutral. However, when the two elements are emanating from a volcano they are (obviously) very hot, and can have positively and negatively charged ions. These in turn cause electric and magnetic fields, with the result that the positively and negatively charged ions separate from each other. This process can then add severe lightning to a volcanic ash cloud.