Re: What would the earth look like from space after nuclear war?

Stephen, 

The best theory on this particularly nightmareish topic gives rather 
unsettling results.  Initially, there will be a brief (1-2 day) increase in 
temperatures.  As the soot, smoke, dirt and other particulates make their 
way to the upper stratosphere, a rapid cooling will take place.  Average 
surface temperatures would likely plumet to about -30F as 85-95% of all 
sunlight is reflected by the dust clouds.  Assuming an exchange between the 
US and Russia that is primarily limited to the Northern Hemisphere, it will 
take several days to weeks for the clouds of dust to spread to the South.  
The total duration of this "winter" period would be highly variable 
depending on weather conditions at the onset and the total number of 
megatons detonated.  Expect about a year though.  Additional problems will 
occur such as rapid desertification of most of the Northern Hemisphere and 
near total depletion of food growing capability world wide.  Should there 
be a great number of nuclear detonations over or under water, several 
billion kilograms of excess water vapor would be injected into the upper 
stratosphere.  This would have a number of bad side effects including 
additional light reflection and additional cooling at the onset.  Later, 
much of the water will precipitate and help wash out the sky, enough excess 
water vapor will remain aloft to cause secondary global warming after the 
dust settles.  Another rather drastic problem would be the near total 
depletion of the ozone layer from the free radicals in the dust clouds 
generated from all the fires on the surface.  Anything on land could expect 
to get rather crispy in this "nuclear summer" phase.  

A number of references for excellent articles by Dr. Robock can be found at 
this website: http://metosrv2.umd.edu/~alan/robock_nwpapers.html

Good luck with your paper! 

Scott Kniffin
Unisys Corp. at NASA Goddard Space Flight Center