Abstract: Heat generated by operating electronic components within an environmentally-sealed enclosure is removed, without direct transmission of a viscous medium through the enclosure. An internal heat sink and external heat sink each span a given wall. The internal heat sink section is baffled and channeled with one place for air to enter, and one to exit. A fan forces air over heat sink extremities of the internal heat sink section. A circulating air column entrapped within the enclosure is drawn into the entrance of the internal heat sink, and forced through the entire length of the internal heat sink, providing for a thermal conduit for a heated entrapped air column to transfer its heat into the internal heat sink. The external heat sink is exposed to the ambient environment, with airflow managed over the external heat sink preferably with a structural surround that provides for channeling of airflow.