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Old 09-09-2010, 07:45 AM
 
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Looking at the average temperatures for Mt Washington, it seems very similar to the sub-arctic such as N Quebec or Labrador except that those places are very dry where as Mt Washington gets a lot more precip than these places do.

How is it that these places have such similar temperatures but one is very dry and the other is very wet?


On a related note, can anyone tell me why the treeline is much lower in New England than at the same latitudes in the western US?

Why is the western US a lot warmer than the eastern US at the same latitudes when adjusted for elevation differences?

Any comments from a meteorologist would be GREAT!

Last edited by ElkHunter; 09-09-2010 at 09:46 AM.. Reason: Removed duplicate post.
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Old 09-09-2010, 11:26 AM
 
Location: USA East Coast
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Quote:
Originally Posted by papafox View Post
Looking at the average temperatures for Mt Washington, it seems very similar to the sub-arctic such as N Quebec or Labrador except that those places are very dry where as Mt Washington gets a lot more precip than these places do.

How is it that these places have such similar temperatures but one is very dry and the other is very wet?


On a related note, can anyone tell me why the treeline is much lower in New England than at the same latitudes in the western US?

Why is the western US a lot warmer than the eastern US at the same latitudes when adjusted for elevation differences?

Any comments from a meteorologist would be GREAT!
Maybe I can help with a few of the questions (I hope):

MT WASHINGTON, NH - Mt. Washington is located at an elevation of 6,288 feet. So mean annual temperatures are considerably lower than a place near sea level or a few hundred feet in elevation.

TREELINE: In North American from what I understand…the treeline is located near 60 North latitude. Supposedly, climatologists think that the 50 F (10 C) isotherm (July) roughly coincides with the poleward limit of tree growth. Even the northermost US/Canadian border areas in the USA…are still well below this line. So I would think tree lines are more a difference in elevation and precipitation. In fact, many interior western states have lower tree lines than many interior eastern states because they are much drier.

WESTERN US/EASTERN US MEAN TEMPS - The warmest areas in the USA are the Gulf and Southeastern states…both in terms of annual mean temperatures and minimum winter temperatures:. Overall…annual mean temperatures in the USA are fairly zonal when you factor out elevation, prevailing winds, and the effects of water masses.




The exception is a narrow strip along the far West Coast States (California, Oregon, and Washington State). These states are warmer than the eastern states at the same latitude for a few months in winter ...because of the prevailing westerly winds that come off the semi-mild Pacific Ocean. San Francisco, CA and Washington Dc (both located about 38 North) are a good example of this: From November to March…San Francisco is warmer than Washington Dc…from April to October… Washington DC is warmer than San Francisco. The direction of the prevailing wind in winter is the chief cause of this. This is also why the Pacific Ocean is so cold compared to the Atlantic Ocean. In the case of the desert areas of the Southwest (AZ, NV) - desert air (dry air) heats up faster than humid air. This is one of the reasons deserts get so hot for so much of the year. At the same time however – deserts cool rapidly at night. So for example Tucson, AZ (32 N) is 5 F warmer than Savannah, GA (32 N) but about 1 F cooler at night in January.

Also, the effect of the mild Pacific is restricted to only the far western states. In fact, outside of the Pacific coast states and the lowland deserts…many places in the West are actually slightly colder in winter than places in the eastern USA. Maryland and Delaware are warmer than northern Nevada at the same latitude in winter for example.

Last edited by wavehunter007; 09-09-2010 at 11:38 AM..
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Old 09-11-2010, 08:38 AM
 
Location: Victoria TX
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Quote:
Originally Posted by papafox View Post

How is it that these places have such similar temperatures but one is very dry and the other is very wet?

!
Dry or humid air is a macro-climatic feature, while mountaintops are micro-climatic. The air over a very large area is either dry or humid. In the case of New England, it is relatively humid, because the general summer warmth can hold a lot of moisture. When that air mass passes over a mountain like Mt. Washington, it retains the moisture, until it cools to the relatively high dew-point and precipitates out.

However, in the subarctic of Northern Canada, the air over a large geographical area is never warm, so it never holds very much moisture, and the climate is much drier.
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Old 09-11-2010, 02:18 PM
 
Location: New York City
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Mountains are generally wet(er) due to orthographic lift. As air passes over a mountain, it rises and cools, releasing moisture.
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