by Gayle Morrow

Ah, spring, when all of our fancies turn to thoughts of, OK, sure, love, but also water. Yeah, water. Every living thing needs it, you know. So is it gonna be a wet season or a dry one? Is the water in that pond warm enough to swim in yet? (I did swim in March once, a zillion years ago.) Is there standing water (or, horror of horrors, ice?) in the garden or can we possibly think about planting something? Is the muddy driveway ever going to be dry enough so we can level out those ruts? Are the creeks running high or low for opening day? When will the snow stop and when will it all melt? (I remember seeing snow cover on a north-facing hillside in June, also a zillion years ago, and, no, not the same year I had that March dip.)

Spring seems to be synonymous with water, for all kinds of reasons, and I got to wondering about some of the terminology and properties associated with that life-sustaining liquid. Specifically I wondered about evaporation, condensation, and hydration/dehydration.

Come on, you wonder about that stuff too, right?

When I think of hydration/dehydration, I think of myself waking up in the middle of one of those the-woodstove-is-really-cooking winter nights in desperate need of a drink of water, or flopping like a tuna because I took a long mountain bike ride on a really hot day and neglected to, you guessed it, hydrate adequately. The simplest definition of dehydration is that it is the removal of water (hydrogen and oxygen molecules) from something. The ways and the whys that removal can happen are numerous—think everything from dehumidifiers, a kind of indoor air dehydrator we all needed last summer when it rained every day, to sun-dried tomatoes, to crisp sheets on a clothes line.

Condensation is the change of matter’s physical state from gas to liquid, usually as a result of the gas cooling. The word is most often used in connection with water—i.e. water vapor to liquid water—although if your kitchen is well stocked you may have a can or two of sweetened condensed milk on a shelf. That essential fudge or poundcake ingredient is milk from which the water has been removed and to which sugar has been added, not to be confused with canned evaporated milk. Anyway, clouds and ground fog are a couple of familiar forms resulting from H2O’s abilities to morph. You can also see it on your eyeglasses when you go from one temperature extreme to another, or on the inside of your windows when the exterior is cold and the interior is cozy. It all has to do with how the water molecules arrange themselves in response to temperature.

Where does evaporation fit in? You can think of evaporation—when heated liquid becomes a gas—as the opposite of condensation. The sun is the primary source of the energy that will evaporate that moisture (but just the right amount, please!) from the garden soil and the muddy driveway. Evaporated water ends up eventually back in the atmosphere as water vapor, and, when conditions are just right, back on the ground at some point as precipitation.

Fairly amazing, isn’t it?