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
I’m no climatologist/meteorologist/oceanologist, but since weather patterns move west to east, and the west side of the US is the pacific ocean which is roughly 2.5 times as wide as the Atlantic, there’s probably more moisture that is in the upper atmosphere after passing over the Pacific than when passing over the Atlantic.
I know that ocean currents have much to do with it as well, not to mention average temps… From what I can gather, the Pacific ocean is a good amount warmer on average than the Atlantic.
I bet if you compared precipitation in South America(controlling for rainforest precipitation) you’d find a similar trend.
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.
Answer: it’s because of the rotation of the earth and the oceans. Basically the sun heats the ocean which puts water in the air. Due to the rotation of the earth the air moves from east to west (kind of, it’s also not inaccurate to say that the land moves from west to east and the air stays put) in sort of a loop north of the equator that goes west near the equator, hooks north as it nears the Americas, goes east back out away from the Americas in colder more polar water and then loops back south along Europe and Africa.
Since air picks up moisture when it’s hot over water and loses moisture when it’s either dry or cold or both you have the most “wet” air on the leg of the loop where it hits the Americas.
The other place you see it even more extreme is the western coasts of Asia where there’s a similar phenomenon but because the pacific is so much bigger pacific storms are even more wet
The distance to water is not what most important. It the water location relative to wind and it temperature that is more relevant and then the US and Europe are a lot more different.
The southern point of Europe is Greece at 34 degrees north. The northernmost point of Texas is at 35 degrees and the southern point is at 25 degrees. In regards to latitude that have a lot to to with climate most of Texas in in Africa not Europe.
South of Texas gulf of Mexico and to the west south-southwest you have the Caribbean and Atlantic. The prevailing winds from around 30 degrees from the equator is to the west. Farther away from the poles wind are mostly to the east. The result is water that evaporates in the warm water close to the equator travel up to the southern US and then turns to the east.
Europe on the other hand has Africa at that latitude and on land, you typically get higher temperatures so North Africa and the Middle East si very dry.
The rain that reaches Europe is primarily evaporation from the cooler North Atlantic with eastern winds that result in less rain.
So most of Europe is further away from the ocean at high temperatures and the right wind direction. Europe is more comparable to Western USA. You do not typically get the extreme amount as some parts of the Pacific Northwest get, that is primarily because there is quite very high mountains but look at Noway and Scottland. But at the same time, the land areas after that do not get as little rain as part of the US. The northern coast of Spain is approximately the same attitude as the Califonia-Oregon border
It is Asia’s east coast that is more comparable to the US east coast. There is more rain in the coastal parts of China, Korea, and Japan where you get a lot of rain. Because of the shape of the coastline and elevation difference the rain falls on smaller areas in the US
There are quite a few explanations, but as with any Europe vs. North America (or really any other continent) there is *significantly* more variation in climate in North America than Europe.
>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).
A lot of this moisture comes in the form of storms like Hurricanes, not’easters, etc. systems that Europe generally doesn’t see. Anywhere on the east coast, especially southeast and New England can see brief (1-2 days) of immense rain/snow accumulation. Most of the eastern US, all the way up to NYC is technically [sub-tropical](https://en.wikipedia.org/wiki/Subtropics?wprov=sfla1).
>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).
I have no idea where you’re pulling your data, but Phoenix Arizona averages only [8 inches of rain a year.](http://www.worldclimate.com/climate/us/arizona/phoenix) the vast majority of it falling in short bursts during the summer monsoon seasons. Heading west, the Mojave desert is even drier. Averages for the state as a whole, and much of the Rockies, Great Basin, and western deserts are largely skewed by winter snowfall in the mountains.
>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.
Much of Europe, especially those close to Mediterranean are in what is aptly called a “Mediterranean Climate” which is characterized very dry summers and ironically require the regions experiencing them to be in close proximity to seas/oceans (I don’t know enough to elaborate beyond that). I can tell you that almost all of the driest places on Earth are actually very close to oceans, they have to be in fact.
Basically, the US is significantly more prone to extremes. I live in a relatively small and climatically “unremarkable” region of the country (New England) and we see temps as high as 107⁰ (42⁰C) and as low as -50⁰ (-45⁰C). We get hit with Blizzards, Nor’easters, Hurricanes, etc.
The north equatorial current (which is both a wind and sea current) is constantly pushing air from the Atlantic over the US east coast. As the air is pushed up over land (and towards cooler climates) it can’t hold moisture and keeps raining until it’s once against pushed out over the atlantic.
With the exception of Ireland/England/Norway/North-western Spain Europe doesn’t have the same moist air pushed over it all the time. The air that flows over the alps tend to be from the much smaller mediterranean.
Overall it’s pretty much the same reason that Europe doesn’t have a hurricane season.
I don’t think it is… there are rainy parts of US and there are dry parts of US. Isn’t it rainy in the UK, Netherlands in Europe?
I live in Norway, my city gets an average of 2500mm a year. 500mm is a bad month, not year lol
I’ll start with Tundras which are the most exaggerated example. Tundras receive an average of 6-10 inches a year of precipitation which is less than most deserts, but they’re usually very wet and boggy.
The simple answer is that evaporation is very slow when it’s cold. I live in a temperate climate and it’s been three or four days since we got about 0.1 inches of rain, yet my driveway is still muddy. Midsummer we might get half an inch of rain in a thunderstorm and the ground will be dry in an hour or two.
Europe is cooler than the Americas due to its higher latitude, the interior of the Russian and Kazak steppes are even moreso.
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