There you are flying along, trying to keep up, and suddenly something tumbles by, gone so fast you didn’t see what it was. A desiccated leaf, a paper cup. If it sparkles, a shred of cellophane or foil. Usually small and harmless… Whatever the ambient air’s doing, most stuff will sink through it faster than we do in our glider, so anything not visibly rising is surely falling. No reason to go back and chase it, but maybe worth wondering where it’s fallen from…
Diverse logics weave together here. Many kinds of detritus take longer to hoist than descend, but fine dust or ash can climb quicker than we do in a booming thermal and then stay aloft for weeks. (Fully ten percent of the earth’s land surface is topsoil deposited by wind since the last ice age, one flake at a time.) Sand, however, even flowing through an air vent two miles above the desert, amounts to very small rocks that hurry straight down when the lift quits. Between these extremes of density, airborne flotsam, natural and manufactured, comes in a spectrum of sizes. The innocuous you don’t need to see ahead of time, but think of anything visible from distance as an unpredictable hazard!
Balloons occupy their own category, whether drifting alone or bound together in fat clusters. If they were sealed truly airtight, they’d expand as they rose until bursting in reduced pressure aloft, and we’d likely never see them. Those we encounter seem to be maintaining altitude, but not so. They’ve been leaking from the moment they were inflated. After rapid ascent to neutral buoyancy, their long fall continues until all that helium has escaped. Balloons so thoroughly outwaft their heavier-than-air competition, you find them caught in brush or fumbling along the ground, still gussied with ribbons and retaining their spheric shape, far deeper into the wilderness than scraps of styrofoam or tissue ever go. Given all this, balloons tell us nothing about the presence of lift — unless they’re out of gas. When you see a flaccid one lofting, do try to follow it!
Pretty much anything else that’s going up by itself marks rising air, obviously, and multiple items near each other expose the richest veins. While you’re at it, also look below them for even more, as evidence of additional lift on its way up… And of course any objects actually circling imply a sure thing, whether lifeless litter or some fellow creature defying gravity. (But oh, beware that angry pie tin at the turn from downwind to base!)
Most debris doesn’t mark lift, it just gets in the way, especially if there’s a lot of it. I’ll admit having tried on occasion to foolishly, spike those ubiquitous shopping bags, just because — and at least once, ‘succeeded’… Should I tell? Oh alright.
We could see the thing was empty, so I aimed straight at it, then glimpsed a streak of logo as it swerved over our canopy, and felt a faint tug at the tail. Turning back, we saw two smaller bags tumbling near each other, each bearing half of that logo. A real bonehead stunt if you think about it, which I hadn’t done, surprise surprise.
The heaviest junk I’ve seen much above pattern height has been an assortment of tree branches; not to say whole limbs, but when a branch’s branches wave gnarly branches, they’re saying go find your own playground! I also thermaled awhile, one smokey evening, with more than a foot of prairie grass growing from a clump of sod big as a football. Yes it was circling, so I ignored right of way and flew against the conspicuous rotation. That poor sod had to know I was flouting etiquette, but didn’t seem to mind.
The biggest non-sentient rubbish I’ve found up there has its own story to tell, but we’ll never get to hear it. Way out in the middle of wide open blue at ten thousand feet, what looked like a huge bundle of laundry hove into sight ahead. It was luffing and furling like a gaudy flag with no pole to hang onto, and we couldn’t resist stopping by for a look. Turned out it was a paraglider, 300 square feet of lightweight fabric, miles from any high ground whence it might have come… and no body in sight! Despite knowing better, I impulsively searched hard and long, all the way down below, as if there’d be anything to see. (Later, asked an expert if someone might have actually fallen from the rig, and he had to laugh. Its pilot was probably seconds from hooking up, he said, when a rogue gust ripped it away.) Now why do you suppose that still gives me the willies?
And then here comes a full sheet of plywood… Well maybe, but the pilot who made this claim is a known exaggerator, so keep your boulder of salt handy. Four feet by eight of quarter-inch ply weighs over twenty pounds, which on impact could deliver a lethal wallop to any aircraft. If you choose to circle with one of those, be sure to go the same direction!
So anyway, just think how fortunate we are that our sky can’t collect indissoluble garbage like the ocean does nowadays, corralling it into vast perpetual whorls. Imagine a gargantuan trashulonimbus of our ‘economic’ excrement stuck up there forever, blotting out the sun. And always growing!
Say what you want about gravity, it has advantages.