1 00:00:00,010 --> 00:00:04,020 What we're seeing are temperatures that 2 00:00:04,040 --> 00:00:08,060 start off quite cold and then when the sky clears 3 00:00:08,080 --> 00:00:12,100 they drop fairly rapidly. 4 00:00:12,120 --> 00:00:16,150 If that conditions persists for a few days, the ground chills, gets quite cold 5 00:00:16,170 --> 00:00:20,180 The ground itself is radiating 6 00:00:20,200 --> 00:00:24,210 away the heat into space, into clear space. 7 00:00:24,230 --> 00:00:28,250 And by getting very cold on the surface, you chill the atmosphere 8 00:00:28,270 --> 00:00:32,280 that's next to this very cold snow. 9 00:00:32,300 --> 00:00:36,300 This lower layer that's getting very cold under the clear sky conditions is denser and it starts 10 00:00:36,320 --> 00:00:40,330 to slide down this huge dome of Antarctica. 11 00:00:40,350 --> 00:00:44,360 What you need is a place where that air is actually caught 12 00:00:44,380 --> 00:00:48,400 and held for a while. So by causing the 13 00:00:48,420 --> 00:00:52,440 air flow to be stationary for an extended period, you get 14 00:00:52,460 --> 00:00:56,470 the absolute lowest temperatures that we're able to find. 15 00:00:56,490 --> 00:00:59,907