San Diego Union-Tribune (Sunday)
Experiencing desert’s first winter rain is a treat for all the senses
The first rain of winter came to the desert last week with attitude.
As I crested the rugged desert ridge, I was slapped by winds whipping at 50 miles an hour along with blowing sand and tiny raindrops that stung as they hit my cheeks.
I pulled my hood a bit tighter around my face since I still had some ground to cover before reaching the shelter of my truck.
The rugged San Ysidro Mountains to the west that normally provide a shield from coastal weather was being overwhelmed by the powerful storm rolling over the ridgetops. Key lights of early morning sunshine would dance briefly on the ridges as misty clouds swirled in the distance.
I paused for a moment and turned my back to the wind to gaze out over the Borrego Badlands and marvel at this magnificent scene of nature’s energies.
Howling wind, blowing sand and raindrops were center stage while the Kabuki dance between sunlight, curdled terrain and brooding clouds created an animated drop curtain background. These were bold forces of nature at work.
More importantly, the raindrops carried the spark of hope that ignites the fire of anticipation for more rain over the winter months followed by a rare, spring wildflower super bloom.
This is an annual ritual of optimism for desert lovers. Unfortunately, a spring super bloom is a rare event and that’s what makes it so special. A spectacular wildflower display may come only once or twice in 20 years.
During those times when rainfall arrives early, is timed right and is abundant, the drab sands will come alive with an artist’s palette of color when the longer days and warmer temperatures of spring arrive.
For months now, the plants and animals in the desert have been collectively holding their breath as they wait for some relief from days, weeks, and even months of searing, triple-digit temperatures.
Yes, they are adapted to live in such conditions, but they wither and wilt to survive until moisture comes with renewed life for another season.
These thoughts filled my mind as I tucked my head from the wind and continued the short hike back to my truck.
But there was also something more and quite subtle in the desert air.
Anyone who has experienced a rainy day in the desert knows about that delicate fragrance that rises to scent the shifting winds.
Many have characterized this pleasant aroma as a perfume. It’s subtle and sweet, like the whiff of a fine cologne floating through an elegant gathering of finely appointed guests.
Take the romance out of it and, of course, there is a name for this.
The official name given for the after-rain aroma is petrichor, defined as, “a pleasant smell that frequently accompanies the first rain after a long period of warm, dry weather.”
The term was coined in the 1960s when Australian researchers wrote about their study that determined it was the oil from various desert plants that created the fragrance after a rain.
Over time, these plant oils seep into the rocks and sand and are activated when pure rainwater soaks into thirsty ground. This post-rainfall fragrance is not unusual in many outdoor places but may differ depending on the plants that grow in a particular area. Forests may produce a different fragrance than grasslands, chaparral or deserts, for example.
Many believe that the smell in the desert after a rain is one of the sweetest and most delicate. There have even been attempts to duplicate and sell the aroma produced by wet creosote oil that comes from this common plant that dots the landscape throughout the desert southwest and Anza-borrego.
The compact but spindly creosote shrubs grow up to 10 feet tall but are most noticeable when they produce small yellow flowers each spring and summer, followed by fuzzy white seed capsules in the fall.
The distinctive fragrance produced by creosote oil has been described as sweet and earthy.
While I appreciate and I am fascinated by the scientists who delve into the empirical reasons for such things as the delicate aroma after a desert rainstorm, I’ll stick with a more romantic answer.
I’d like to think this beautiful scent of nature is from all the desert plants joyfully exhaling in the rain after another summer of survival.