Invention that changed the World in 1902: Air conditioner by Willis Carrier
Genius can strike anywhere. For Willis Carrier, it was a foggy Pittsburgh train platform in 1902. Carrier stared through the mist and realized that he could dry air by passing it through water to create fog.
Doing so would make it possible to manufacture air with specific amounts of moisture in it. Within a year, he completed his invention to control humidity – the fundamental building block for modern air conditioning.