How long would the Earth last if the sun became a black hole?

[LibraryOgre]

OK, let's use that desert example. In the first 12 hours without sunlight, temperatures drop by over 40º. If that rate holds up, it'd take three days to get down to -200º, for the nitrogen to condense out of the air. And that rate won't hold up, because heat loss by radiation is strongly dependent on temperature, so as the temperature drops, the rate of temperature decrease will slow dramatically. And now consider that, over timescales of multiple days, heat transfer from elsewhere on Earth will be relevant, and most of the Earth's surface is covered with water.

For a fictional reference, see "A Pail of Air" by Fritz Leiber. Bear in mind, it's "50's sci-fi magazine" science fiction.