Short answers, pulled from the story.
Wladimir Köppen published the first version of his climate classification system in 1884. He continued to refine the approach based on botany and meteorology until his death in 1940.
German climatologist Rudolf Geiger took over the work in 1954 and introduced further adjustments through 1961. Their combined effort created what is now known as the Köppen, Geiger climate classification.
Group A covers tropical regions where every month averages at least 18 degrees Celsius. Group B includes arid and semi-arid areas defined by low precipitation relative to evaporation potential. Group C represents temperate zones with mild winters but warm summers. Group D encompasses continental climates featuring cold winters and warm summers mostly found north of 40°N latitude. Group E contains polar climates where even the warmest month stays below 18 degrees Celsius.
Wladimir Köppen designed his entire framework around botany rather than abstract meteorological data alone. The system allows scientists to predict which vegetation types dominate a region based solely on climatic metrics.
Arid zones cover approximately 14.2 percent of Earth's land surface and include hot deserts like those in North Africa and cold deserts such as the Gobi in northern China.