Kitty Wellman, Age 10, Of East Lansing, Mich., for her question:
How do geysers go against gravity?
We take it for granted that water runs downhill. A river winds its way down the gent1e slope of a continent to the sea. Streams rush and gush down the lofty slopes until their waters settle quietly in the basin of some mountain lake. But the rule, it seems, can be broken. Once in a while a ,jet of water squirts up toward the sky.
Water is a liquid, and a liquid cannot stay in place without help. It needs a floor and sides before it can come to rest. When poured on the ground, it must flow and slide downhill until it settles in the sea, a lake or in some shallow hollow, such as a puddle. In the kitchen, water slops all over the floor unless you pour it into the sink or into some container, such as a kettle.
If you put the kettle of water on a hot stove, it will boil. And the boiling water will act somewhat like the steamy fountain that spurts up from a geyser. It will disobey the rule that says that water must flow downhill. It will go against gravity which pulls it down to the solid ground and spurt up into the air. The plume of foamy steam coming out of the spout of a boiling kettle is a miniature, gravity defying geyser.
When water changes to steam, the liquid becomes a gas. Suddenly it needs more room, more space. For gas always needs much more space than a solid or a liquid. When water boils and becomes steamy gas, it grabs itself more space in a hurry and explodes outward in every possible direction. A geyser is one of nature's kettles with a furnace
And a pot of water deep in the rocks below the surface of the ground. We find the geyser in a region where volcanoes were busy in the last million years or so. The top of the seething lava has cooled, and the surface of the ground does not feel hot. But the cool crust is a seal above layers of hot rock still buried deep below ground. There are cracks and crevices in these buried hot rocks. And there are trickles of rainwater and melting snow seeping into the buried pockets.
The roots of a geyser are deep pockets and pipes. They fill up with seeping ground water and heat it to boiling point. The water may remain below until it is far above boiling point. Then the steamy mixture must explode with a rush to get the extra room it needs. Its exploding energy is strong enough to defy the force of gravity. Up it spouts through a crack in the ground and squirts a foamy fountain into the air.
The plumy fountain from a geyser may look like a stream of ordinary water. Actually it is not. It is a mixture of water vapor and misty steam with perhaps just a little liquid water. While the showy display is going on, liquid ground water already is trickling down to re fill the underground kett1e. The frothy fountain of steam and gas must have hundreds of times more space than the liquid water. The only place it can get this extra space is up in the air.