Five Parts Per Trillion

The dirt had been cracking for weeks. Soren pressed his thumb into one of the cracks and it went down past the second knuckle, dry all the way, the way a cookie is dry, the way an old sponge is dry.

His great-uncle Bo sat on an overturned bucket between the tomato cages, fanning himself with the seed catalog. He had been promising rain since Tuesday. The radio promised it too. The sky just sat there, pale and heavy, doing nothing.

"You can smell it coming," Bo said. "Old farmer's trick. Half an hour before, you smell it."

Soren didn't say anything. He didn't believe in smelling weather. Weather was pressure and water and temperature. None of those had a smell. He kept his face polite and his doubt to himself.

But he started paying attention to his nose anyway, because there was nothing else to do.

The garden smelled like hot tomato leaves, which is a green, sharp, almost peppery smell. It smelled like the warm plastic of the watering cans. It smelled like Bo's coffee going cold in the thermos. None of it smelled like rain.

The first drop hit the path two feet from his shoe.

It made a small dark coin on the dust. Then another, on his arm, cold. And then the smell arrived, and it arrived so fast and so completely that Soren actually stepped back.

It was not a faint thing. It was not a hint. It came up off the ground like something released from a trap, dark and round and mineral and alive, a smell with a shape to it, a smell that filled the whole inside of his head in one breath.

"There," said Bo, not even opening his eyes. "Told you."

But Bo had it backward. The smell hadn't come before the rain. It had come with the rain. After. The drops landed and then the smell, like the ground was answering.

Soren crouched down over the spot where the first drop had hit. He put his nose almost to the dirt. The dry dust there smelled like nothing, like warm and dust and nothing. He waited. Another drop landed beside his hand and the smell bloomed up again, right there, right out of the spot the water touched.

The rain was making the smell. Not announcing it. Making it.

He sat back on his heels with rain starting to speckle his shoulders and tried to take it apart the way he took everything apart. The water itself had no smell, he knew that. So the water was hitting something in the dirt, and the hitting was throwing something up into the air, something that had been waiting down in the dry ground the whole pale silent afternoon.

Something alive, maybe. The dirt was full of alive things. He had read that one spoonful of soil held more living creatures than there were people on Earth, and he had not really believed it, the way you don't believe a number that big. But the smell was so specific, so much like a thing made on purpose, that the number stopped being words and became this. Some of them, down there, had been making this all summer, holding it, packing it into the dry crumbs, waiting.

The rain came harder. The whole plot lit up with the smell now, every drop a tiny hammer knocking it loose, thousands of them, a whole field of it rising at once.

Soren stood up into it. He thought about how little of the stuff there had to be. The smell was enormous and the source was a few specks of bacteria in a thumbprint of dirt. That meant his nose was catching almost nothing and reading it as everything. A trace. A whisper of a trace.

Later he would learn the number, and the number would be worse than he guessed. Five parts per trillion. He tried to picture a trillion of anything and couldn't. Five drops in enough water to fill the swimming pools of an entire city, and his nose caught it from across the path before the second drop fell.

He stood there with his eyes shut and let it pour, and he understood that his nose, this thing in the middle of his face that he never thought about, this thing he used mostly to tell if milk had gone bad, was an instrument so fine it could find five parts in a trillion of one particular molecule out of the whole crowded air.

Bo was right that you could smell rain. Bo was just wrong about everything underneath it. It wasn't a trick and it wasn't the sky. It was the ground talking, and it only talked when the water knocked.

Soren had spent the whole summer thinking he was the strange one, the kid who tested what grown-ups said instead of nodding, who needed the mechanism before he'd believe the magic. He'd doubted Bo to be polite about it. And his doubt had walked him straight into the real thing, which was stranger than the trick Bo believed in. The polite nodders were still sitting under the awning. He was out here in it, in the proof, getting soaked.

He took out his notebook before it could get wet. The first drops were already starring the cover. He wrote two words and the number with a question mark, and then he tucked it back inside his jacket against his chest where it would stay dry.

Bo finally stood up off his bucket, holding the seed catalog over his head. "You coming under the awning or not?"

Soren shook his head.

He knelt back down at the edge of the path, where the dust was only half wet, where there was still dry ground waiting. He held his hand flat above it. A drop fell past his fingers and struck the dust, and the smell jumped up to meet him, brand new, made fresh in the half second it took to reach his face.