What is the reason for the series of car crashes?

In Florida, a series of car crashes happened along a major highway over the weekend. At least 12 cars and seven tractor-trailers were involved in these accidents. Ten people were killed in the wrecks. More than 12 other people were taken to hospitals.
    Chad Myers spoke about why the smoke was covering the highway. He also talked about the conditions that led to these crashes over the weekend.
    "(7) The highway was covered in smoke from a nearby brush fire. That made it very difficult for drivers to see. The fire in the swamp and in the forest was only 60 acres, not that big. But in a regular fire, smoke goes up and keeps going up. But in Florida, it didn’t keep going up. The reason is because there was a layer of warm air up here. So as soon as the smoke tried to go up, it hit the layer of warm air and came back down. It’s called inversion. The smoke was trapped near the surface. It couldn’t go away. People drove into the smoke and they hit cars that were already stopped in the roadway".
    Before the accident happened, the roads had been closed for three hours, and then the smoke cleared a bit because the wind blew some smoke away. However, in half an hour after they re-opened the road, the crashes happened and 10 people died.
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