(WGHP) – After a train with cars containing toxic chemicals derailed in East Palestine, Ohio, on Sunday, officials scheduled a controlled release to avoid an explosion. The controlled release created a thick, black plume of smoke that was visible from weather radar on Monday. 

The plume reached a certain level in the atmosphere and was unable to continue to rise, and so it began to spread out like a thick cloud. 

The smoke was trapped from rising higher into the atmosphere due to an inversion layer at around 3,000 feet. 

What is an inversion layer? 

An inversion layer occurs when cooler air is near the earth’s surface and warmer air is on top. When air parcels try to rise into the warm air above, they become cooler than the surrounding environment and they aren’t able to ascend any higher. 

Since warm air rises, any air that is underneath the inversion layer is not able to escape because it is cooler than the air above. This then leads to the trapping of smoke and pollution closer to the ground. 

What are signs of an inversion layer? 

Some of the signs of a temperature inversion include: clear skies, calm winds, close to sunrise or sunset, the presence of dew on plants/surfaces, horizontal smoke patterns and ground fog in low-lying areas. 

In the instance of the toxic chemicals being trapped in East Palestine, the presence of an inversion layer was clear due to the horizontal smoke pattern that occurred as the plume rose higher in the atmosphere. Once it reached approximately 3,000 feet, the smoke stopped rising vertically and began expanding horizontally.