Answer: as thick as single roof
Explanation: The earth is actually about 8000miles thick Xmas, with the atmosphere been 300miles thick. Comparing this or Assuming the earth three story building, it atmosphere would on be as thick as the single roof. The whole of earth needs to be atleast 20 times bigger or thicker than its atmosphere, same should apply to the building and it's roof
Population density can change due to immigration and emigration > True :}
~ Drought hazard is generally high for semiarid areas, such as Northeastern and Southern South America, Northern, Southwestern and Horn of Africa, Central Asia, Australia, West U.S. and the Iberian Peninsula; and low for tropical regions, such as the Amazon, Central Africa and Southern Asia