Using a high-speed camera to photograph lightning strikes is an effective method to study and better understand the phenomenon of lightning.
Marcelo Saba, a researcher at Brazil’s National Institute for Space Research (INPE), and graduate student Diego Rhamon, took this rare image showing the connection between lightning strikes and nearby lightning rods . Engineering on March 14 reported. The new study was published in the journal Geophysical Research Letters.
Lightning rods try to connect to the downward current. (Photo: Diego Rhamon/INPE).
To take pictures, the team used a system of high-speed cameras installed on the roofs of high-rise buildings. The photo was born thanks to good planning and luck when taken at the right time, helping to reveal details about parts of the lightning. According to the team, the image shows a negatively charged lightning bolt hitting the ground close to the ground at a speed of 370km per second.
“When lightning is several tens of meters above the ground, lightning rods and tall objects atop nearby buildings discharge positive charges upward, competing to connect with the downward lightning,” Saba said. The last picture was taken 25 milliseconds before the connection occurred and lightning struck one of the buildings.
Saba started researching lightning with high-speed cameras in 2003, building one of the largest databases of high-speed lightning videos.
The team used a camera that captures 40,000 frames per second. The high-speed equipment allows them to assess the impact of such lightning strikes, especially in the absence of appropriate protective measures. In this case, a fault in the installation caused the area to open and the 30,000 ampere current to strike caused significant damage.
There are a total of 31 channels of lightning precursors (also known as precursor rays) that are launched from nearby buildings to block the descending negative progenitor rays, according to the team.
Lightning can also be classified as negative or positive depending on the charge transmitted to the ground . Experts estimate that only 20% of lightning contacts the ground, the rest is confined to the clouds.
According to the team, such lightning bolts can be up to 100km long and carry currents as strong as 30,000 amperes. “The temperature of a typical lightning bolt is 30,000 degrees Celsius, five times the surface temperature of the Sun,” Saba said.
Lightning forms due to friction between ice particles, water droplets, and hail, releasing an electrical charge and creating polarization between different cloud regions. Such potentials can range from 100 million volts to 1 billion volts. Since the charges want to follow the path of least resistance, lightning will branch, often in a zigzag pattern instead of a straight line.
“The path of lightning is determined by the different electrical properties of the atmosphere, which are not uniform,” explains Saba. Lightning rods do not repel or attract electrical currents, but only provide lightning an easy and safe path to the ground, the team said.