What happens in a cloud to cause electrons to move from some particles to others?

Air molecules and suspended water droplets collide as they swirl around in the clouds. Warmer air and water droplets rise, carrying charges with them. The result is an excess of positive charge near the cloud tops, and an excess of negative charge in the bottom layers of the clouds.

they are knocked off some ice and added to other ice as they crash past each other

Explanation:

firearm identification is the process of analyzing the bullets and cartridge cases left at a crime scene to determine if they came from a particular firearm. marks on the bullets and cartridges may be common to every firearm of that type. these are called class characteristics.

your answer is, orbit around the nucleus