Ambient heat is a new feature of version 50. It can also be called "air temperature."

As it's name suggests, it is heat currents that travel along air currents. To view Ambient Heat, turn it on in the menu and switch to heat display (6)

https://lh6.googleusercontent.com/-w4oDOOtCGxw/TfrqZoh90RI/AAAAAAAAAa0/21EjdJGGWR4/s800/Ambient.gif

As you can see, the entire field of play is surrounded by heat, the normal 22C. If you were to place a very cold object (say, a GOL cooler)

https://lh5.googleusercontent.com/-jQIy3sYoDV8/TfrqZ6AjtCI/AAAAAAAAAa4/DgMhfdrLuFg/s800/Ambient2.gif

The air temperature would begin to change. Like pressure, it is blocked by walls. Therefore, it is completely possible to combine the Decor layer and Ambient Heat to create a fully stocked fridge!

https://lh4.googleusercontent.com/-_QxZNOxvZCY/TfrqaO4lSlI/AAAAAAAAAa8/ne5I0saV1yI/s800/Ambient3.gif

Ambient heat cannot be directly influenced by the player in the fact that the heat/cool tool cannot affect the ambient temperature. The value of ambient temperature at a certain point can be seen on the HUD by activating debug mode(Hotkey D).