Sensory Overload!
FLASH!!!….BANG!!!…RRRRUUMMMMMMBLLLLLLE…
SMELL THAT!
Like the rest of humanity, as is evident by Thor/Zeus and other mythologies, I’ve always been fascinated by thunder storms and lightning. As a kid I took advantage of every opportunity to bear full witness to these events as and when we were privileged enough to be gifted them.
27 October 2024 provided another phenomenal display, so I rushed to collect my camera and tripod to attempt the challenging endeavour of photographing bolts of lightning striking terra firma…never an exact science.
Speaking of science, lightning bolts are immensely powerful discharges of electrical current (+-100 000V) between two hyper-charged points. These discharges occur either cloud-to-cloud or cloud-to-ground depending on conditions. What we witnessed on 27th October was a spectacular example of cloud-to-ground with literally more than a hundred visible strikes from our stoep.
Setting the shutter to remain open for 30sec at a time allows for capturing multiple strikes in a single exposure when things are busy…and it was.
As the storm approached from the NNW it drew closer and closer…I got more and more excited. Some strikes were quite close by as we could only count to 3s between the flash and thunder which equates to about 1km distant.
The sudden and incredible heat dispensed by these strikes causes air molecules to expand so rapidly that it creates an explosively percussive shockwave which can be viscerally felt all the way to the core of your bones.
Bolts at proximity are deafening with volumes in excess of 200dB and can be heard over 40km distant!
Regular exposure to any sound beyond 83dB will inflict permanent damage to a human’s ears…good thing thunderstorms are infrequent occasions.
Sporadically shifting the camera’s vantage to where majority of the strikes occurred, yielded an incredibly fortuitous capture of two separate bolts, each connecting with some poor tree, instantly igniting them with the 28 000C a bolt generates!
* Note the distinct orange light on the ground where the wood erupts in flame
This often is the only way some of these large leadwoods and mopanes are ignited as they are just too dense (1200kg/m3) for normal veld-fires to bring to flash-point.
In the darkness between flashes we could clearly see the flames of a growing fire in Maseke and with the accompanying wind it threatened to become a concern.
Almost as soon as the flames started licking higher than the trees, a very familiar and intoxicating aroma drifted on the wind…Petrichor…and that means RAIN…a curtain of rain which proceeded to immediately extinguish any and all flames…crisis averted…
Petrichor’s Greek roots are petr-(rock) and īchor (the fluid that flows through the veins of the gods) and is the collective term for a cluster of contributors which makes rain smell like rain.
Geosmin, a compound produced by bacteria in the soil.
Stearic acid, exuded by plants during dry weather as a germination-inhibitor for their own seeds. This acid is dissolved in rain (which triggers the seeds to start growing) and becomes an aerosol which contributes to the aroma.
Ozone, created by lightning splitting oxygen (O2) atoms, which then rejoin to form ozone (O3).
All these components are generously released by the first rain after a very hot/dry spell. Humans detect these hydrocarbons @ 5ppt (parts per trillion) which is more sensitive than sharks are to blood in water at 1ppm (parts per million). The evolutionary origin is likely to be linked to our need to find wildlife (who’ll follow the rain) to hunt, grow crops, graze our domestic animals or take shelter from the approaching storm…but it’s just conjecture.
What however isn’t, is that I shall continue to expectantly look skywards and smile with every aural or olfactory hint of an approaching storm!
Yours in Wonder,