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The main reason why Phoenix is warmer than Atlanta is that it's in the desert...and Atlanta is in/at the base of highlands. In the valley where Phoenix is - strong surface heating, due to intense solar radiation, a bare ground (deserts acquire heat much more rapidly than oceanic/humid climates), and most important, a location on the east side (stable side ) of the subtropical high, allows the interior of AZ to warm quicker than most locations at it latitude.
However...places in southeast like north Georgia and Tennessee are in/or at the mid base of highlands…so they get much colder than locations on the coastal plain of the Southeast…even in Georgia. For example, St. Simons Island, GA (on the Georgia coastal plain) has a January high of 63 F …close to the ave January high of 67 F in Phoenix, 65 F of Tucson, and warmer than the 57 F high in Las Vegas.
Mts vs the coastal plain can make a big difference anywhere in the USA.
I think Pheonix is more protected from Arctic air incursions because there are tall mountains nearby which block most of it. Atlanta is much more exposed.
The main reason why Phoenix is warmer than Atlanta is that it's in the desert...and Atlanta is in/at the mid base of highlands. In the valley in central AZ around Phoenix...strong surface heating, due to intense solar radiation, a bare ground (deserts acquire heat much more rapidly than oceanic/humid climates), and most important - a location on the east side (stable side ) of the subtropical highs produce a climate that heats up very quickly. Humid and oceanic climates...with more cloud cover, humid air masses, and a green forests, don't heat up as much as deserts.
In winter...places in Southeast USA like north Georgia and Tennessee are in/or at the mid base of highlands…so they get colder in winter than locations in the interior Southwest or locations on the coastal plain of the Southeast however - even in Georgia. For example, St. Simons Island, GA (on the Georgia coastal plain) has a January high of 63 F …close to the ave January high of 67 F in Phoenix, 65 F of Tucson, and warmer than the 57 F high in Las Vegas. The 52 F ave high in January in Atlanta shows how well highlands can change temp even over a short distance.
Mts vs the coastal plain can make a big difference anywhere in the USA.
Thanks WH. But even places on the coastal plain are still cooler in the East. St. Simons Island, GA is 2.5 degrees latitude farther south then Phoenix and at lower elevation (Phoenix is at 1,100 feet). Charlston SC is a fairer comparison and its January high is only 57F.
Like you said, western US is warm for its latitude. This is true for southern Arizona and northern Montana. Only places very high in elevation are cool.
Thanks WH. But even places on the coastal plain are still cooler in the East. St. Simons Island, GA is 2.5 degrees latitude farther south then Phoenix and at lower elevation (Phoenix is at 1,100 feet). Charlston SC is a fairer comparison and its January high is only 57F.
Like you said, western US is warm for its latitude. This is true for southern Arizona and northern Montana. Only places very high in elevation are cool.
My point was really that cities on the coastal plain are a good bit warmer than cities in the highlands...and a much more fair comparsion. Yes, some cities in the west are warmer at the same latitude...but much less so when you compare the coastal plain cities. Atlanta's 52 F to Phoenix's 67 F in January is a bit misleading. Just for the record…both Charleston and Savannah, GA (close to the same latitude as Phoenix) average 59 F and 60.4 F respectively in January:
A good example is Tucson, AZ is located just about at 32 N…as is Savannah, GA. The normal January highs are 65 F and 60.4 F respectively… 4.6 F is not all that far apart. It's a much more fair comparsion than Atlanta or places in TN in the highlands I think.
I think Arctic air masses can penetrate more easily further south in the SE USA vs. the SW USA if you look at record cold temperatures and also might bring the averages down a little in the SE USA vs. the SW.
Also, the point about the dry desert air heating up faster makes a lot of sense and why the SW USA tends to be a lot hotter year round than the SE USA.
Pheonix and Atlanta may be at similar elevations but as WH pointed out, the geography of the 2 places are totally different which also help explain. Atlanta is at the base of highlands whereas Phoenix is in a valley surrounded by tall mountains which help to trap the heat and also to a certain extent block the cold.
My point was really that cities on the coastal plain are a good bit warmer than cities in the highlands...and a much more fair comparsion. Yes, some cities in the west are warmer at the same latitude...but much less so when you compare the coastal plain cities. Atlanta's 52 F to Phoenix's 67 F in January is a bit misleading. Just for the record…both Charleston and Savannah, GA (close to the same latitude as Phoenix) average 59 F and 60.4 F respectively in January:
A good example is Tucson, AZ is located just about at 32 N…as is Savannah, GA. The normal January highs are 65 F and 60.4 F respectively… 4.6 F is not all that far apart. It's a much more fair comparsion than Atlanta or places in TN in the highlands I think.
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I dunno if Atlanta is any more "highlands" then Phoenix is. As I said, they are both at the same elevation (in fact Atlanta is marginally lower)
Tuscon is at almost half a mile above sea level (2398 feet). Savannah is at 50 feet.
If you don't like Atlanta, how about Columbia, SC (state capital) since it isn't right on the coast. It's on the coastal plain and below 300 feet above sea level. Its January high, according to Wikipedia, is 55.1F - full 12 degrees lower than Phoenix.
You seem to be picking all the coastal locations - you might as well go with Bermuda which is actually warmer than Phoenix in the winter. But Phoenix is hundreds miles away from any body of water. I'm not at all surprised that coastal California has mild winters. But the inland deserts in the SW, it seems, are almost as warm.
Instead of Tuscon, how about Yuma which is at much more reasonable 138 feet ASL. 70 freaking degree avg Jan high - warmer (slightly) than even Daytona Beach, FL (which is more then 3 degrees farther south and on the coast).
Location: The western periphery of Terra Australis
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Quote:
Originally Posted by MrMarbles
I dunno if Atlanta is any more "highlands" then Phoenix is. As I said, they are both at the same elevation (in fact Atlanta is marginally lower)
Tuscon is at almost half a mile above sea level (2398 feet). Savannah is at 50 feet.
If you don't like Atlanta, how about Columbia, SC (state capital) since it isn't right on the coast. It's on the coastal plain and below 300 feet above sea level. Its January high, according to Wikipedia, is 55.1F - full 12 degrees lower than Phoenix.
You seem to be picking all the coastal locations - you might as well go with Bermuda which is actually warmer than Phoenix in the winter. But Phoenix is hundreds miles away from any body of water. I'm not at all surprised that coastal California has mild winters. But the inland deserts in the SW, it seems, are almost as warm.
High mountains shield southern Arizona from the northern cold.
You seem to be picking all the coastal locations - you might as well go with Bermuda which is actually warmer than Phoenix in the winter. But Phoenix is hundreds miles away from any body of water. I'm not at all surprised that coastal California has mild winters. But the inland deserts in the SW, it seems, are almost as warm.
It’s just really hard to find two locations across a mainland 2500- 3000 miles apart…that have the same geographic perimeters and try to compare their temperatures. From years of researching.. I kind of remember than at least in the USA in winter…temps seem to be pretty zonal (east/west) across the USA when you factor out geography. I think what confuses people is that certain areas in the far southwest interior are deserts and favored by unique geography (like Death Valley…or the central Valley around Phoenix…etc). Take another example (not on the coastal plain!) between two places one in the Southeast and one in the Southwest:
Albuquerque, NM 35 North
January High/Low – 48 F/24 F
Raleigh, NC 35 North
January High/Low – 49 F/29 F
Here is a map of mean January temps (high/low)…parts of southeast VA are 10 to 20 F warmer than southern Utah at close to the same latitude...parts of northern New Mexico are 10 F colder than the Mts of TN…southern Nevada is about the same as northern North Carolina at the same latitude (36 North). Look how cold parts of the central western states are compared to the central eastern states. However, there are other factors at work…meaning its just really hard to find two locations with equal parameters.. However, the fact remains the largest area of warmth in winter is in the USA is in the Gulf/south Atlantic states...most of the west is cooler. In fact, take out CA and AZ ...and almost everywhere in the West is cooler than in the East :
As far as Wikipedia for climate data - use NOAA, they are the one and only source!
You have to consider elevation. Large swaths of the west are very high above sea level. Albuquerque is a mile up. Distance wise, Utah, NM and northern Arizona are not far that from Phoenix and shouldn't be much colder. But Phoenix lies much lower than all those places and is therefore significantly warmer. This is kinda hard to tell on these maps.
Quote:
Originally Posted by Trimac20
High mountains shield southern Arizona from the northern cold.
Probably. And if any cold air mass comes through, it is warmed by adiabatic process.
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