Since we are talking total energy release, it becomes hard to compare them since a meteorite dumps a significant amount of it's energy into the atmosphere in a

Since we are talking total energy release, it becomes hard to compare them since a meteorite dumps a significant amount of it's energy into the atmosphere in a much slower and widespread fashion, whereas a nuclear device does it in one place at one time. Now I'm pretty sure that if you get a big enough meteorite moving fast enough, the distinction becomes much fuzzier and the real important factor becomes just how much thermal energy was added to the atmosphere.