PETRICHOR
Michael Ellis

As the rain fell on the thirsty earth last week a wondrous marvel occurred. Delicious smells emanated, then enveloped and delighted my nose. And if you were lucky enough to be near, but not too near, lightning strikes, you could also smell the ozone created by the powerful electrical energy discharge.

Smell is our most primitive sense. It dwells in the reptilian stem or limbic part of the brain. The same place where lust, flight, aggression, and memory dwell. Odors are not processed by the higher functions of the brain and unlike all the other senses, smell is wired directly to the limbic system, it bypasses our more evolved, thinking brain. That is one reason it is so difficult for us to assign words to odors and the reason that smell is so evocative of memory.

It always rains a couple of time in August and September and these rains are usually associated with hurricanes. Last week Hurricane Linda spawned air masses that came up from the south off Baja California bringing warm, moisture-laden clouds. Another uncommon phenomenon associated with these hurricanes in the San Francisoco Bay Area is lightening. We generally only have three or four lightning days per year along the coast — that’s all. The mixture of warm air and cold air helps to create the enormous electrical potential for lightning. And as most of us know, only too well, we usually only have cool air masses meeting other cool air masses. This, of course, is due to the cold water of the Pacific Ocean here.

In 1964 two Australian researchers coined one of my favorite words – petrichor – for the scent of rain on dry earth. It comes from the Ancient Greek – petros for rock – and ichor – the blood of the gods in Greek mythology. I really enjoy the idea that we can smell the blood of the gods emerging from the earth after the first rain.

This is Michael Ellis with a Perspective.

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December 1, 2010