PC science
As far as nuclear Winter, Russell Seitz wrote of Sagan's TTAPS model in blistering terms: "instead of a planet with continents and oceans, the TTAPS model postulates a featureless, bone-dry billiard ball. Instead of nights >and days, it postulated 24-hour sunlight at 1/3 strength. Instead of realistic smoke emissions, it simply dumped 10-mile-thick soot clouds into the atmosphere instantaneously. The model dealt with such complications as east, west winds, sunrise, sunset and patchy clouds in a stunningly elegant >manner -- they were ignored."