Image above: A rare sight, copious rain in the Namib desert - riders enjoying the first smell of rain in over a decade.
The sublime earthy scent of rain falling on parched earth - particularly after a long drought in arid areas such as the Namib desert - is beyond description. There is even a word for it…
The word petrichor derives fro the Greek ‘Petra’ meaning ‘stone’ and ïchör, the ethereal blood that flows in the veins of the gods of Greek mythology. Thus comes the expression ‘the Blood of the Stone.’
The heady aroma - one has to experience this at least once in your life - is said to derive from oils exuded by plants during dry periods to retard seed germination. In the presence of moisture, the oil is released along with geosim, a metabolic by-product of bacteria emitted by wet soil producing that distinctive euphoric-producing bouquet. The aroma is released as aerosols - small bubbles which float to the surface of rain drops - carrying bacteria from the soil.
The lighter the rainfall, the stronger the aroma. It doesn’t even have to rain - just moisture in the air causes the pores of rocks and soil to open and flush the oils. When it does rain the scent is spread in the wind to the delight of all within its reach. Image above: riders head into what turned out to be a rain storm of note! An exceptional experience in a desert....
In the presence of lightning, another distinctive scent is added to the mix - ozone. It seems that lightning spilts oxygen and nitrogen molecules in the atmosphere and they in turn can recombine into nitric oxide which reacts with other chemical in the atmosphere to form ozone - a sharp smell faintly reminiscent of chlorine. While this description might not instil rapture….the combination of the two aroma’s out in the middle of the desert has an extraordinary effect which touches some ancient part of us, long neglected.
Whatever the science behind the wonderful smell, it matters not to those who have had the privilege of being there to enjoy it….
Picketed horses watching the approach of rain