Thunderstorms become charged through a process where ice crystals and graupel (soft hail) collide within the storm cloud, leading to a separation of electrical charges. The upper part of the thunderstorm cloud becomes positively charged while the middle to lower part of the thunderstorm cloud becomes negatively charged.
The Charging Mechanism
The charging of a thunderstorm isn't a simple process, but it mainly happens because of collisions between different types of precipitation particles within the cloud. The key players are:
- Ice Crystals: Small ice particles floating within the cloud.
- Graupel: Larger, denser ice particles that often form when supercooled water droplets freeze onto ice crystals.
These particles collide due to updrafts (rising air currents) and downdrafts (descending air currents) within the thunderstorm.
Charge Separation
When ice crystals collide with graupel, charge is transferred.
The larger and denser graupel is either suspended in the middle of the thunderstorm cloud or falls toward the lower part of the storm. The result is that the upper part of the thunderstorm cloud becomes positively charged while the middle to lower part of the thunderstorm cloud becomes negatively charged.
Charge Distribution
The charge separation leads to a distinct charge distribution within the thunderstorm:
| Region of Cloud | Charge |
|---|---|
| Upper part of cloud | Positive |
| Middle to lower part | Negative |
This charge separation creates a strong electrical field within the thunderstorm, eventually leading to lightning when the electrical potential becomes too great.
