SWIR sensors are there for hot burning lights. LWIR (aka thermal) sees things that are every day temperatures. Both wavelengths have better transmittance through fog than visible light so we say those sensors can 'see through' fog. The physics comes down to the wavelength of the light vs the size of the molecules of the medium the light is trying to get through [1].
Another fun part is that fog at one airport can be different than fog at another, so while the weather conditions at both locations may say visibility is "Runway Visible Range (RVR) 1000ft", that is for a pilots eyes, and the same camera may work just fine at one location and not at all at the other.
Another fun part is that fog at one airport can be different than fog at another, so while the weather conditions at both locations may say visibility is "Runway Visible Range (RVR) 1000ft", that is for a pilots eyes, and the same camera may work just fine at one location and not at all at the other.
[1] https://upload.wikimedia.org/wikipedia/commons/e/e9/Atmosphe...