Different sound-convection patterns can make a difference as can the strength of the thermal layer.

Occasionally the goggles could be fooled by thermal layers in the air.

Take us below the thermal layer we charted this morning.

"It depends on how well we're able to follow the thermal layer," said Sparrow.

We both feel fine; maybe we've hit some kind of thermal layer.

The submarine was fading now, perhaps slipping down below the thermal layer, trying to hide.

A thermal layer would have helped their evasion.

They scanned the planet's thermal layers down to nearly forty-five thousand kilometers.

Core down to the thermal layer and, big as it is, this whole complex could be warmed in the winter months.

The nitrogen in the thermal layer kept the container at just above freezing, rendering the virus inactive.