This week’s question comes from Morning Brief reader Michael, who asks, “Can you measure how many gallons of water fall in a storm?”

Meteorologist Jonathan Belles: The answer to that is yes. Or, that is the simple answer.

For instance, I was looking for Hurricane Harvey, which is one of our biggest rainmakers in the United States, and apparently Harvey dropped roughly 27 trillion gallons of water when it made landfall in Texas in 2017.

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To find that number, experts looked at the area of rainfall, the actual size of the rainfall footprint and how much rain fell in that area. Because Harvey rained for six or seven days, some spots got 60 inches of rainfall.

The easiest way to find that number for a storm would be a very straight forward equation:

Area (square feet) x Rain (inches) x 0.623 = Gallons of Rain

But I want to put a big asterisk next to that equation. This is the complicated part of the answer.

Doing volume multiplied by area only works in the world of Minecraft where everything is a cube. The real world is much more complex.

A century ago, when somebody saw a cloud and asked, “How much is that going to rain?”

The easiest way to answer that is with a cube. Build the cube the length and the width of the cloud and put it directly under it. The cloud drops all its rain, and it fills the cube 2 inches deep. Now you can do the math.

But say you get a little side cloud that has half as much water. Well, you keep adding those little slide clouds out and about, and you're going to get a much different picture of how that storm is going to drop rainfall. We've all been there, in that storm where somebody's getting dumped on and the next person over is saying, “It's just sprinkling here.”

The truth is you can estimate how much a storm drops, but there are a ton of variables: how big the storm is, how strong the storm is (rainfall rate) and how dry the atmosphere is. Storms don't drop rainfall uniformly. The fringe of a storm will have lower rainfall rates while the core will have heavier rainfall. The actual answer is always more complex than simple equations allow.

Do you have a question to ask the meteorologists at Weather.com? Write to us at [email protected] and we’ll pick a new question each week from readers to answer.