In 1985, a passenger jet landing at DFW airport was forced to the ground by an unusual downward blast of wind called a downburst. The plane struck cars on the highway and a water tank, then crashed on the airfield, killing more than 100 people.

It was the third such fatal crash in a decade. So, the FAA set out to invent a new warning system for these dangerous wind events. A downburst is a sinking column of air within a thunder cloud that accelerates toward Earth, reaching speeds over 100 miles an hour.

When it strikes the ground, it blasts out in all directions, like a mammoth version of water splashing in a sink. These winds are strongest just 10 to 30 feet from the ground and travel horizontally outward in all directions. They can fell trees like a tornado’s whirling winds, but they all fall in the same direction, like dominoes.

For aviation, the first step was training pilots to look for visual signs – expanding rings of dust on the ground below, or sharply defined shafts of intense rain.

Technologically things were more complex. Vulnerable airports installed a network of wind sensors, as well as advanced Doppler radar that could track wind speeds. All fed into an early alert system.

By 1994, 46 high traffic airports had installed these systems. They haven’t had a single downburst accident since -- and technology continues to improve. A triumph of aviation safety.

Sand is incredibly common. There are oceans of it – in oceans, and deserts too. But, for our purposes, that’s not the right kind of sand.

We use sand in concrete, to make bridges and roads, buildings, houses and power plants. We use it in glassmaking, for windows, computer chips, solar panels and much more. We use it for hydraulic fracturing, to prop open cracks in shale deposits so oil and gas can flow.

In all, we use billions of tons of sand every year. But only a certain kind will do.

Beach sand is often mixed with salt. If used in concrete, it can corrode the reinforcing steel. And the grains of beach sand, and especially desert sand, are often rounded by waves or wind. Concrete needs angular grains that lock together. Hydraulic fracturing needs hard grains that can withstand pressure. And glassmaking needs almost pure quartz.

That means, for most uses, the ideal sand is angular, well-sorted quartz. And that’s only found in a few places.

Rivers and streams are natural sorting machines. They break down and wash out weaker minerals, leaving quartz sand in bars and banks, which can be dredged or mined. Through time, many of these quartz sand deposits were lithified into sandstone, which today can be ground back into sand.

Our demand is so great that this once common material is becoming scarce, spawning a lucrative international trade -- for the right kind of sand.

Plastic has remarkable value to humans. But it’s also a major source of ocean plastic pollution.

Most of it is nets and rope from fishing boats, or municipal garbage that’s carried down rivers into the ocean. There it accumulates in spinning gyres of plastic, twice the size of Texas.

Large pieces eventually break down into fragments and microplastics. But because plastic is made to be durable, it won’t degrade any farther than that.

Wouldn’t it be great if we could clean it up?

That’s what a Dutch teenager thought when he was diving in Greece and saw more plastic bags than fish. He created a high school science project -- that has since grown into an international nonprofit, called The Ocean Cleanup, employing engineers, marine biologists and collection teams.

They set up huge U-shaped nets that float with the current in the spinning gyres, in the top few feet of water where most plastics (but few fish) are. These gradually capture the debris, which their boats collect and haul to shore.

They’ve also installed collection systems at the mouths of rivers to intercept plastic before it enters the ocean. Together, their systems have captured millions of pounds of plastic waste, which they sort, recycle or properly landfill.

There’s much more to do, but they’ve inspired governments and other nonprofits to work on plastic waste management on land and at sea.

Hopefully, with growing awareness, we can all make a meaningful difference in ocean plastic pollution.