I've just done some googling for a nice diagram that looks like the one that explained it to me from my physics book when i was in high school, came up with
this, ok, it's talking about mirages but it explains the basic concept.
As for infrared refracting less than other waves, you've probably got a point that it would refract less. but then, you've got an infrared image, which i would like to try once or twice, but i wouldn't want it for every photo (not sure about the OP).
The lion photo i saw in London at an exhibition for the
Travel Photographer Of The Year at the royal geographical society or something (just opposite The Albert Memorial and around the corner). probably finished now anyway. But i fully intend to enter next year, i've got over 20,000 photos from a few years in europe and asia, something's gotta be worth showing...
So i did at least remember that it was shot at 40mm, even if it was a nikon. the description of how he took it was from the back of an open-sided safari ute/truck thing, mounted to a mono/tripod upside down, holding by the feet of the tripod and either timer or remote/cable release (i think remote release). it would be nice if they put those descriptions on their website though...