There’s a fair amount of discussion about why Europe is (for its latitude) so much warmer than America, but I can’t seem to find any explanations about why Europe is so dry compared to America.
To explain what I’m talking about, I’ve been looking into the climate data on Wikipedia of European and American cities recently and have noticed a very sharp difference their average precipitation levels. Specifically, European cities consistently seem to receive around 20-30 inches (about 500-760 mm) of rain a year whereas American cities east of the 98th degree longitude (about in the middle of Texas) receive somewhere between 40-60 inches (around 1000-1500 mm). The only European exceptions seem to be western parts of Ireland, the UK, and mountainous areas like northern Spain.
Even American cities in the plains west of the 98 receive rain comparable to places like Volgograd (between 15-20 inches) and places like Phoenix receive rain about equal to Atyrau (a Kazakhstani city on the north coast of the Caspian).
What makes this especially odd to me is that Europe, as a geographic entity, seems like it should receive more rain than America, given that most land in Europe is substantially closer to water compared to most places in America.
In: Planetary Science
To get a lot of rain you need a moisture supply (a warm, shallow ocean) and a cold air supply to make the warm, humid air dump the moisture.
Parts of Europe do have the moisture supply in the Mediterranean, but they don’t have the vast Canadian arctic to the north to help that moisture crash out.
Storm systems in the US tend to draw moisture from the Gulf of Mexico and then dump it over the eastern half of the country when that air encounters cold air from the north.
The western half of the country mostly lacks this moisture supply and is extremely arid.
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