How Do You Say How Big a Really Big Fire Is?

Here's an ongoing debate in our newsroom as we move into autumn and what is often the climax to our fire season: What's the best way to describe the size of a wildfire? In acres? Square miles?

Hectares? (Just wanted to see if you're paying attention.)

An instructive comparison of some kind ("the Rim Fire has burned an area nearly eight times the size of San Francisco")?

One reason the question comes up is because the Associated Press, the most widely used U.S. news agency, has switched from using acres to square miles. If the AP announced the rationale for the change, I've never seen it, and I've never gotten around to asking them.

At the same time, our main firefighting agencies -- Cal Fire for state jurisdictions and the U.S. Forest Service and National Park Service, among others, for federal lands -- stick religiously to acres.

Thus: Fire managers report the King Fire now burning in El Dorado and Placer counties is 89,574 acres. AP (and news outlets that just repeat what the agency reports) will say 140 square miles.

The result is some editorial disorder that may matter only to those handling news broadcasts and news-type blog posts.

At KQED, some anchors, reporters and editors use square miles. Some use acres, as I do. My rationale: I'll stick with the unit the fire agencies use. But there's more to it. Part of it might be blind traditionalism -- if acres were good enough for Mark Twain, they're good enough for me. And part of it might be that I can visualize an acre, which was about the size of the lot my parents had when I was growing up in south suburban Chicago. Of course, imagining 89,574 of those lots is a little bit of a stretch.

Others say they've got a better handle on what a square mile is than what an acre might be. I know what they mean. I've always thought that Midwest folk knowledge consists in part of the following truths, passed down from the Northwest Ordinance of 1787: that a square mile contains 640 acres; that a square mile is called a section, and that 36 sections in a 6-by-6 grid comprise a township.

The folk knowledge is borne out before your eyes if you fly across the country. When you come to the great Gridland that lies (mostly) east of the Missouri River, north of the Ohio and west of the Alleghenies, you see an endless expanse of land sectioned off into rectangles.

In northern Illinois, for instance, most of those rectangles are squares delineated by roads at 1-mile intervals. They thus outline square miles, and if you're in a plane going 540 mph, about 9 of those mile squares will slide by every minute. Check it out on your next fly-0ver journey.

All that gives you something to work with when you're trying to imagine 90,000 acres or 140 square miles or whatever. But face it: For most of us, a piece of territory that big sprawls beyond comprehension.

Which leads us to the homely comparison with the area of a city or county that we all know. Last week, after the King Fire expanded, I tried describing it this way: "The fire has burned 73,000 acres and is 10 percent contained. That’s about 115 square miles, or the equivalent of the San Francisco Peninsula from the Golden Gate down to Pacifica and Millbrae."

Which is OK, especially if you live in one of those places. But it assumes that people can visualize that area. So my next effort was to try to show the fire's footprint, as determined by data files provided by federal agencies (provided daily), superimposed on a map of the central Bay Area.

My first effort (near the top of this post) used the fire's footprint from last Saturday in its original cartographic orientation (with the axis in a southwest-northeast direction). We got feedback: 1) Does anyone notice the fire outline is sort of phallic? 2) You should have aligned the axis of the fire with the axis of the San Francisco Peninsula.

Well, we can't do much about 1). But as to the second observation, we rotated the axis of the footprint image. I'm not sure it makes the point any more strongly, but there it is.