Regarding the size of and very cold cloud-top IR brightness temperatures seen with Typhoon Haiyan, the IR images (courtesy of Rick Kohrs, SSEC) show a side-by-side comparison with Hurricane Katrina. Haiyan has been artificially superimposed at the same location over the Gulf of Mexico. Note the significantly colder cloud-top IR brightness temperatures associated with Haiyan (-80 to -89 ºC, violet colors), due to its location in the tropics (near 10 ºN latitude) where the tropopause was much higher and much colder.