Wine 201: Water

Maybe it's more of a 401 and nobody cares. Idk. I hope you like chemistry

Water. The source of all life!

Water is important not only to keep vines alive as nutrition and for cell structural support. It also has great connections to what we talked about previously: the balance of acidity and ripeness of grapes. And all roads lead to this point!

The concept of water we’ll talk about today is not how much water vines need, but rather various forms of water and how they affect the ripeness levels in different part of the world.

Bodies of water & moderating influences

Before we go into the larger picture of water vs. grapes, let’s review water in its essence. Welcome back (again) to high school chemistry class.

Water. H2O. Two hydrogen atoms and one oxygen atom, sharing electrons in covalent bonds. As a whole, the water molecule has ten protons and ten electrons, so it’s neutral—but the sharing of the electrons is not equal. In this covalent bond, the oxygen atom attracts electrons a bit more strongly than the hydrogen atoms, aka there’s a slight negative charge near the oxygen atom and a slight positive charge near the hydrogen atoms. This makes water a polar molecule.

Wait, don’t go! Stay with me.

Because of these charged poles, water molecules attract one another based on the positive or negative ends, and form what are called hydrogen bonds. As they move and slide by one another, water molecules constantly form and break hydrogen bonds.

Ok, so why the hell am I talking about water at a molecular level? Because this structural understanding will help us fully grasp the concept of heat capacity, which will in turn allow us to make the connection between bodies of water and grape ripening.

Heat capacity (or thermal capacity) is the ability of a substance to hold heat without becoming hot itself, or more scientifically, the amount of heat required to raise the temperature of one gram of a substance to one degree Celsius. For water, you need 1 calorie—and that is the highest of all substances.

This is because for other substances, heat affects the molecules directly, warming them up quickly. Water reacts differently to heat, which must break up the hydrogen bond before heating up the molecule. But again, because hydrogen bonds form constantly in water molecules, they are formed as soon as they are disrupted by the heat, and during all this, the temperature is maintained. For the temperature to rise, individual molecules must heat up and since that’s possible after the bonds are broken, this drastically slows down the warming of water.

The inverse is also similar: when water cools, the molecules form hydrogen bonds with one another first, maintaining the temperature as they do, causing temperature drop to slow down.

So basically, having a high heat capacity means water can minimize changes in temperature, warmer or cooler. (Fun fact, this is also why our bodies, which are made up of about 65% water on average, excel in moderating body temperature)

Ok. Now we can go back to the grapes.

Since water retains temperature for longer periods of time, it’s crucial for wine growing regions, both for warm and cool climates, where bodies of water act as moderating influences.

Since water holds heat better than soil, large bodies of water like oceans or lakes have less dramatic shifts in temperatures from day to night. After the sun sets, the water remains relatively warm, while the land next to it drops in temperature significantly.

Remember from the previous Wine 201 post where we talked about the temperature vs density of air. Warmer air rises; cooler air sinks. As the temperature on the land drops after the sun sets, the warmer air from the ocean rises to land, and the cooler displaced air replaces it. This extends the warmth on the land. When it’s warm on the land, cooler air blows in from the water, moderating the heat on the vineyards during the daytime.