How many different classifications are there? Where would Phoenix and Melbourne fall on the list?
Five (oversimplified) classifications:
A - tropical (hot year-round, and seasonal or year-round rain.)
B - arid (evapotranspiration > precip)
C - temperate (warm to hot summers, mild winters, moderation to significant precip)
D - continental (mild to warm summers, cold winters)
E - polar
It's rather a lot to go into here, but basically, Phoenix is in the arid classification. Its designation is the hottest and driest possible - BWh (which admittedly makes more sense if you speak German).... B / Wueste (= desert) / heiss
Melbourne is in the temperate classification, Oceanic subdivision. It would be in the Mediterranean subdivision, except the rain there is not seasonal as it is in L.A., Cape Town, Adelaide, and the Algarve.
The wiki page for all this is here:
http://tinyurl.com/yobyyfWould you agree that Royal Melbourne is the "World Class Course" built in the most arid climate?
I apologize in advance for getting semantic on you, but it depends how you define things. If Royal Adelaide is world class, that's a somewhat more arid climate. And I am not sufficiently familiar with L.A. microclimes to judge aridity, but I can tell you that Riviera probably gets 30% less rain than Royal Melbourne.