Reference

The electric field strength in a thundercloud plays a crucial role in lightning formation. Here's how it affects the process:

1. Charge Separation: Within a thundercloud, charge separation occurs, typically with positive charges accumulating at the top of the cloud and negative charges at the bottom. This separation creates an electric field.

2. Field Strength and Lightning Initiation: Despite the known charge separation, the electric fields observed in thunderclouds are often much weaker than the dielectric breakdown strength of the air. However, certain processes can enhance the field locally, leading to conditions favorable for lightning initiation.

3. Leader Formation: The lightning initiation often begins with the formation of a "leader," a channel of ionized air that grows through the cloud. The presence of electric fields influences the development of these leaders.

4. Enhanced Fields: Factors such as variations in cloud density, the presence of ice particles, and the distribution of different types of hydrometeors can locally enhance electric fields, aiding in overcoming the air's resistance to forming a conductive path.

5. Modeling and Observations: Studies have highlighted that the effect of electric charge on ice particles can reduce the electric field required for lightning strokes by a significant factor. Models and observations suggest mechanisms like the initiation of positive streamers can lower the effective field needed for lightning inception.

For more detailed information, you can refer to these sources:

• Radiation Electric Field in Thunderclouds
• Lightning Initiation Hypothesis

These insights show that while the overall electric field might be weak, localized enhancements can be sufficient to trigger lightning.