Final answer:
The upper region of a thunderstorm cell generally has a positive net charge, and the lower region has a negative net charge. This separation of charges leads to a strong electric field and the occurrence of lightning discharges.
Step-by-step explanation:
The net charge in the upper region of a thunderstorm cell is positive, while the net charge in the lower region is negative. This separation of charge generates a large electric field within the storm cell and is a crucial factor in the development of lightning. During storm conditions, clouds can form localized electric fields that can be larger and reversed in direction. The charge distributions depend on local conditions, which can vary, but generally, the upper parts of thunderstorm clouds tend to accumulate a positive charge, while the lower parts tend to accumulate a negative charge.
The negatively charged particles within the storm cell will move toward regions of lower potential, and it's this migration of charge that contributes to the lightning discharge process when a pathway is established for a current to flow, typically towards a positively charged area either within the cloud, in a different cloud, or towards the ground.