The resource is very plentiful.
Tiny solid and liquid particles suspended in the atmosphere are collectively called aerosols
A. Globalization is the answer
1.We have access to space to see it is round
2. We have 24 hour time zones. How could it be noon in one place and midnight in the other?
3.We are able to study lunar eclipses and see how they work (greeks discovered the earth is round with that method.).
4. Why do ships slowly sink into the distance? Exactly
5. Surveying other planets.