Understanding Lightning: What Science Still Can't Explain
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Lightning is often thought to be a rare occurrence, but in reality, it strikes multiple times, defying common misconceptions. For instance, the Empire State Building is hit around 23 times annually. Here's a video showcasing it being struck three times within mere seconds:
Contrary to popular belief, scientists are still piecing together the puzzle of how lightning functions. According to Ningyu Liu, a physics professor at the University of New Hampshire, the genesis of lightning remains enigmatic even after more than 250 years of exploration. Liu's research is part of a larger effort that has unveiled surprising new findings about lightning's behavior.
Another contributor, Brian Hare from Groningen University in the Netherlands, recently identified previously unseen "lightning needles" within thunderstorms. He reflects on the current state of lightning research, noting, “We still don't fully grasp how lightning initiates, develops within clouds, connects to the ground, or why it behaves in such peculiar ways afterward.”
To understand the current knowledge base, we should look back at the history of lightning studies. The serious examination of lightning dates back to 1752, when Ben Franklin's kite experiment did not actually involve a lightning strike, but rather demonstrated the interaction between electricity and storms. This laid the groundwork for significant advancements in lightning research, although progress remained slow for a considerable time.
By the late 1800s, scientists had begun using photography to capture the phenomenon of lightning, and recent slow-motion videos have further expanded our understanding.
Today's consensus is that lightning originates in turbulent thunderstorm clouds, where powerful updrafts and downdrafts create the necessary conditions for electrical discharge. The following steps outline this process:
- Collision of Ice Particles: Ice particles collide, leading to the separation of charges.
- Charge Distribution: Smaller particles gain positive charges while larger ones become negatively charged, resulting in a charge difference as lighter particles are pushed higher.
- Air Resistance Breakdown: When the charge builds sufficiently (in the millions of volts), the air’s resistance fails.
- Formation of Plasma: This breakdown produces plasma, a conductive gas.
- Development of Leaders: Two plasma channels, known as leaders, emerge, moving in opposite directions based on their charges.
- Connection with Opposite Charge: Leaders search for oppositely charged areas or objects to connect with, resulting in a lightning event.
- Return Stroke: If a bolt reaches the Earth, a return stroke occurs, creating the observable flash in a fraction of a second.
Nevertheless, significant gaps still exist in our understanding of these processes. For instance, while scientists are aware that the air "breaks down," the exact mechanism remains elusive, especially within the clouds.
Liu elaborates that while electric fields must exceed certain thresholds to trigger breakdown, measurements have revealed that the maximum fields in thunderstorms often fall short. There are theories suggesting that ice particles in clouds might enhance local electric fields, but clarity on how this leads to the initial lightning channel formation remains lacking.
Recent studies have introduced further complexity. Instead of the previously accepted notion of "fast positive breakdown," Liu's team found evidence of "fast negative breakdown," indicating that lightning initiation might be more complex than previously thought.
Hare's team also contributed to the conversation by identifying needle-like structures in lightning, which may explain why lightning can strike multiple times during a single event. This finding contradicts earlier beliefs about how charge flows, underscoring the need for more in-depth research.
Despite the knowledge that lightning can hit the same spot multiple times, the reasons behind this phenomenon are still being explored. Various factors, such as the height of an object or its conductive properties, can influence the likelihood of being struck.
In conclusion, while advancements in lightning research have illuminated some aspects of this complex phenomenon, many questions remain unanswered. The intricacies of why some lightning remains in clouds while other bolts reach the ground are still not fully understood.
Although lightning poses risks, fatalities have decreased significantly due to increased awareness and improved safety measures. Today, individuals are statistically more likely to face dangers from other sources than from lightning.