Here come the trees. The energy is palpable. Sky will be interrupted, even blocked, by masses of green that will last until fall. Every time I walk outside, birds sing it, insects hum it, flowers dance it. Last weekend, our senior dog was somewhat terrorized by the near deafening trill and croaking of neighborhood frogs. I actually had to cover my ears when passing through a particularly loud spot. From mighty oak to graceful maple, something exciting is going on and everybody knows it. Sap is rising. Buds are getting ready to break. Some have already burst.
Do you know what's even more astonishing? Tree sap is not pushed up from below by root pressure as was once believed. It is pulled from above. Let me say that again-- it is pulled from above. The process is still being researched and it appears to require little to no energy input from the tree to lift sap as high as 100 meters. It's all about physics and the power of the sun. Wondrous. Can you feel it? Get out there and hug a tree.
Thinking optimistically, this long string of gray, rainy days will end. Meanwhile, the permeating and powerful scent of rain is hard to miss. This time of year it is a promise of things to come. Spring is here, even if it's coursing mostly underground and our bodies are still desperately craving a boost of vitamin D.
So what about the scent of rain? A little background - in the 1960's, Dr. Isabel Joy Bear and Dr. Richard Thomas of Australia's national science agency named the unique smell that accompanies rain after discovering what forms it. Their paper, The Nature of Argillaceous Odour, was the first to define petrichor as the earthy scent that occurs when rain falls on dry earth. It comes from the Greek "petra," meaning stone, and “ichor,” meaning the ethereal blood of the gods.
So how is petrichor created? To greatly simplify, during extended dry periods, plants and soil bacteria release various compounds. When rain drops collide with the earth, the compounds combine and aerosolize to become the unique scent we now call petrichor. Petrichor is most pungent after a dry spell, in the moments when rain first begins to fall.
Human noses are highly sensitive to the scent of rain. Researchers believe recognizing petrichor on the breeze is important to animal survival because it allows us to anticipate and locate coming precipitation. Some people find the scent disagreeable. I like it. How about you?
Artist and naturalist Michelle Louis has a vigorous curiosity about the natural world. She walks with intention in wild places at least 1,200 miles yearly, much of it on the Ice Age National Scenic Trail. She makes art documenting her experience along the way and in her studio.