Smokey the Bear causes forest fires. Well, he sort of makes them worse.

I'm only half joking here. In the early 1900s, forest fire prevention and firefighting policies specifically campaigned to suppress all fires and we got very, very good at it.

Smokey the Bear, introduced in 1944, was an effective part of the campaign. The problem with all of the fire fighting, though? Undergrowth started to build up.

As it turns out, ecosystems have actually evolved to deal with fires. For example, many trees actually require fire in order to sprout their seeds. Which means that we “need” regular forest fires in order to clear out undergrowth, so that new growth can fill in.

If that undergrowth isn't cleared out—say, due to people preventing forest fires for decades—when a fire finally does occur, it's likely to be a full crown fire, instead of a relatively harmless and beneficial ground fire. A crown fire is one that grows large enough to burn material up in the tops of trees and completely wipes out all vegetation in a region.

This can lead to massive surface erosion, wildlife die-offs, alteration of surface chemistry, and many other negative consequences. Some crown fires can grow large enough to become firestorms, which create their own wind systems.

Here's a crown fire:

For comparison, here are the aftereffects of a ground fire, in time lapse:

Since the 1960s, though, scientists have recognized and begun pushing steps to correct the problem. Controlled burns have become much more common in the decades since, and the expenses involved in running them safely are more than recouped by the lack of damages from much larger, more dangerous fires.

So, Smokey the Bear did develop from a wrong-minded way of looking at wildfire control, but he still does serve one important purpose: controlled burns need to be started by professionals. If you're camping in the woods, be careful with your fires.

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Quotable

Oh, Yard Ramp Guy, only you can prevent bad quotations:

“The grass is always greener around the fire hydrant.”

— Jeff Rich

That's me, looking for cashews.

Anyone who's worked in shipping—or anyone who has ever opened a jar of mixed nuts—has experienced the same thing, over and over again: When you're moving a jumble of little stuff, the big items (or Brazil nuts) always end up at the top.

At first glance, it seems simple enough: the smaller stuff can just fit down into the holes between everything else. Problem solved. Except...if that were true, then the small stuff would be at the bottom but the big stuff would still be scattered all the way through.

Well, what about density? If the big items are just less dense, they'd pop right to the top, yes? Well, sometimes, though much denser large objects also tend to rise to the top. It's only the items with a slightly different-than-normal density that remain scattered throughout.

In order to understand this, we need to view it a bit differently. Let’s approach it in terms of convection. In a liquid, temperature and pressure differentials can create convection currents that move particles around in huge looping patterns. If you treat the mixed nuts as a fluid, convection actually starts to accurately model what's going on. (Scientists call it granular convection.)

As it turns out, both of our previous ideas were almost right. As we move the box around and shake its contents, we force the particles in the middle upward in a current. The particles on the sides then fall into the gaps left by the rising particles in the center. Which is where our first idea comes into play: the smaller particles can fit down into the new gaps more easily, leaving the biggest ones on top.

Found 'em.

We still have the density issue confusing things, though. And this we can't solve quite as easily. We know what happens, and we have an idea how it happens (weirdly enough, density doesn't particularly affect granular convection on this scale if the mixture is in a vacuum), but we still haven't put our fingers on all the whys.

One thing is for sure, though: Cashews are definitely the best. You'd have to be a fool to think otherwise. (Well, the almonds can stay, too.) Brazil nuts and all the rest are just something you have to endure for the sake of the cashews.

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Quotable

Good thing people never run out of things to say. My Quote-Off with that other Yard Ramp Guy continues:

“God gives the nuts, but he does not crack them.”

— Franz Kafka

Me, pondering food.

I've written a lot about the shipping industry in this space. Everything from forklifts and pallets to roads. In fact, I write about roads almost more than anything else. One thing I don't write about so much is the actual stuff being shipped.

Shipping fresh food has been a goal of human civilization since…well, always. You can only maintain a certain level of population with food gathered in your local area. Agriculture increases the maximum potential population level, but only up to a point. The ability to ship food from other areas results in even higher potential populations. It also provides a safety buffer for times of famine. If one harvest goes bad, ship a surplus from somewhere else.

For a long time though, there weren't a lot of good ways to ship food. You could transport some grains, spices, and oils in decent ways. Fresh fruit and vegetables, however, were another matter. Meat could be shipped, but only if it was smoked or—more usually—salted.

The downside: these preservation processes resulted in lower nutritional quality. Scurvy was a risk on long sea voyages exactly because of this.

So, the average person's main diet was of food grown very near to him and her—usually within a few hours' walk. For larger distances, livestock had to be moved while still alive; hence those giant cattle drives in the Old West, and railroad cattle cars.

Pouring ice into a railroad car.

The refrigerator railroad car changed all that. Insulated cars had ice tanks at either end, with vents allowing the cooler air to flow into the cars to preserve meat and produce. This rapidly resulted in the practice of transporting various local foodstuffs across huge distances.

One interesting side effect of this is that many of the fruits and vegetables we eat today aren't necessarily the best tasting or most nutritious. They’re the ones most easily shipped and preserved. Many fruits are picked before they're entirely ripe. If you've ever had a ripe peach off the tree, you'll immediately be able to taste the difference. I won't eat grocery store peaches anymore if I can help it.

Pawpaws, a fruit native to the East Coast, are generally agreed to be one of the most delicious fruits you can find. (I can't stand them, but I've never met anyone who agrees with me on this.) Lots of folks use them in place of bananas in their cooking. Why aren't they sold in grocery stores everywhere? They bruise easily and only last a couple of days after being picked before going bad.

Or: In Space, No One Can Hear You Take out the Trash

My family goes to a lot of movies. We're not film buffs, by any means. Usually, we're looking for snappy dialogue and explosions. A couple years ago, we saw the film “Gravity.” For those who haven't seen it, a runaway debris cloud destroys satellites and space stations. Even though the science in that movie was pretty badly off, in a lot of ways, something like it does have the potential to occur.

Kessler Syndrome is a hypothetical scenario dreamed up by a NASA scientist named Donald Kessler in the 70s. Essentially, it proposes that if enough objects are in low Earth orbit, collisions between them will eventually result in an enormous cascade of debris.

It's a pretty simple process: one piece of space junk slams into another, which sends debris scattering about. Some of that debris hits another piece of space junk, creating another burst of debris, which slams into more space junk, and then maybe into a satellite. Eventually, you have an enormous cloud of debris traveling through orbit. Each piece would be widely spaced, but even tiny bits can have insanely destructive power when moving that quickly. The cloud wouldn't take out every satellite, of course; it would stay in the same orbit, and many satellites would be in a higher or lower orbit.

A Kessler cascade could potentially make space travel impossible for millennia, completely blocking off that orbit. The debris wouldn't orbit forever. The drag from the miniscule amount of air at that altitude, along with a few other factors, would eventually clear the orbit again, though the process could take thousands of years.

Governments take the threat quite seriously. Satellites aren't allowed to launch unless they can be safely disposed at the end of their lifespans. The two most common techniques for doing so: dropping it back into the atmosphere or raising it up into a higher graveyard orbit. People also have proposed gadgets for clearing the debris, including a device called a laser broom, which is precisely as cool as it sounds.

It all really just goes to show: proper waste disposal is important, no matter where you are.