Storm in a Teacup: The Physics of Everyday Life(86)

Perhaps, down there, as the Pacific Ocean glides past, a blue whale is making sound waves, calling into the gloom. If we could watch that sound traveling beneath the ocean surface, we would see it traveling outward like ripples on a pond, taking an hour to reach California from Hawaii. But the sound is hidden in the water, and no evidence of it is visible from up here. The oceans are filled with sound, overlapping pressure oscillations pulsating outward from breaking waves, ships, and dolphins. The deep rumblings of Antarctic ice can travel underwater for thousands of miles. From our viewpoint on the edge of space, you would never know that any of it was there.

Everything on the planet is spinning, traveling once around the Earth’s axis every day. As winds travel across the spinning surface, they tend to keep going in a straight line, although friction with the ground and confinement by the air around them constrains their path. From up here, we can see that the winds in the northern hemisphere tend to turn to the right, relative to the ground, as they carry on in spite of the spin of the Earth. So weather, especially the weather farther away from the equator, spins. Hurricanes rotate, and so do the smaller storms that we can see rolling across the oceans. The eye of the storm is the hub of each wheel, and each wheel must spin because the Earth spins.

Over Antarctica, thick snow clouds are gathering. Inside each one, billions of individual water molecules exist as a gas, jiggling around with the oxygen and nitrogen. But as the cloud cools, they are giving up their energy and slowing down. When the most sluggish molecules bump into a nascent ice crystal, they lock on, each in a fixed place in the ice lattice. As the snowflake is buffeted up and down inside the cloud, the molecules on all six sides of the original crystal find themselves in the same conditions, and stick in the same way. Molecule by molecule, a symmetrical snow crystal is built. After hours of slow growth, the crystal is large enough for gravity to win the battle and it tumbles from the bottom of the cloud. Below is the Antarctic ice sheet, the largest agglomeration of ice on Earth, stretching sideways for thousands of miles and down for thicknesses of up to 3 miles. The accumulation of ice is so heavy that the continent itself has been pressed downward under the additional weight. But every molecule of that white expanse fell in a snowflake, and the pile of snowflakes has been growing for a long time. Some of the water here has been frozen for a million years. In that time, the molecules have vibrated about their fixed crystal lattice location continuously, but never fast enough to become a liquid again. In contrast, the molecules being pushed out of Hawaii’s volcanoes as lava are only just dropping below 1,100°F for the first time since the Earth was formed, 4.5 billion years ago.

At the heart of Earth’s outer engine is the energy supply from the Sun. As it heats up the rocks, ocean, or atmosphere, or as it fuels sugar production in plants, it’s pushing the engine away from equilibrium. As long as there’s an imbalance in the distribution of energy, there is always the potential for things to change. The movement energy of falling rain can erode mountains as it splashes down on bare rock. The vast excess of heat energy at the equator drives tropical storms, battering palm trees, redistributing water from sea level to high mountains, and sending waves crashing onto beaches. The energy stored in a plant will be used to build branches, leaves, fruit, and seeds, eventually running out of usefulness as low-level heat. Only the seed will be left, a package of genetic information destined to restart the cycle with new energy from the Sun’s fountain of light. Our planet lives because of the constant injection of energy from above, feeding the engine and preventing Earth from winding down into stable, unchanging equilibrium. From up here on the edge of space, we can’t see the tiny details, but we can see the big picture: Energy flows onto Earth from the Sun, trickles down through the ocean, the atmosphere, and life, and eventually carries on out into space as the planet radiates heat away. The same amount of energy goes in and comes out. But the Earth is a gigantic dam in the energy flow, storing and using this precious resource in myriad ways before it’s released to the universe.

As we drift back down to ground level, a beach now looks like a process instead of a place, a patchwork of timescales and size scales. The ocean waves are carrying energy from storms far out at sea. As they break on the beach, they rattle the sand and rocks, grinding them together. One speck at a time, the stone is chipped away, each pebble sculpted by millions of random collisions. It takes a millisecond to remove one minuscule chip, but years of slow attrition to make the pebble smooth. In geological time, a beach is temporary. It will last only if the supply of new pebbles and sand is greater than the loss as they wash out to sea. Over months and years, sand will shift into the sea and back out again in response to the ocean. We love our tidal beaches precisely because we can see the ebb and flow reshaping the sand twice a day; it’s as though the slate is wiped clean, and we find the simplicity of the newly smoothed sand satisfying. But this daily remodeling hides the decadal shifts as our coastline grows and shrinks in front of us. The life in the rock pools thrives on change, adapted to periods of being high and dry alternating with spells of complete submersion. Though a casual glance at a rock pool can give the impression of a museum exhibit behind glass, in every pool there is a fierce battle for resources going on. The resources on offer are all ultimately very simple: access to the drips of energy oozing through the Earth’s system or the chance to gather the molecular building blocks needed to construct a life. More than anywhere else, a beach exemplifies the transience of life. When the energy and nutrients are available to support life, rock pools flourish. During the barren periods, life will be found elsewhere. Species evolve by altering their use of the physical toolbox available to them one genetic mutation at a time. Whether they’re harvesting energy, moving around, communicating, or reproducing, they are all just using the same principles in different ways.