`  ::As an aside, the temperature issue is also quite interesting. NIST shows some figures of simulations in which the fire first heats up to 1.000 °C in parts of the northern side, then the fire moves to the south, heats up there, while the northern side is cooling down. The northern side did not collapse, but the southern side did (with minimal differences in simulated temperatures). At the same time, the buildings are supposed to have collapsed symmetrically due to a fire which was, according to NIST's own report, very asymmetric at the time of collapse. NIST also apparently overestimated the oxygen consumption of the fire by assuming that available oxygen would be burnt instantly (i.e. gaseous products of the fire would have to move away instantly etc.) It was a rather calm (i.e. not windy day), however, and there is no evidence of any ``chimney`` effect, i.e. much of the smoke is exiting the tower through the (broken) windows, which are also the entry point for the oxygen.  `