Clear something up about thermal layers

[SteamWake]

I have always been of the belief that when your hiding beneath a thermal layer it is best to do so only a few meters below the layer.

That if you go deeper than that it is easier to pick you up

In other words therma layer at 140 feet it would be harder to detect you at 150 feet than if you were at 210 feet.

True or false?

and is this modeled in the game?