Life zones are geographic areas that
are defined by the plant and animal life and living conditions within
them. They are used by scientists to
recognize patterns in the natural world, and are determined by a number of
factors including elevation, precipitation, and temperature. What makes understanding the distribution of
life zones so difficult is the complex relationship between natural variables
across the globe. The Koeppen system is a classification system used to
describe Earth’s main climate groups according to latitude, degree of
continentality, and location relative to topographic features (Richs, R).
There is
a strong correlation between latitude and elevation regarding plant and animal
life. The correlation between these two
factors is positive; for every 1,000 miles in latitude, similar plant life is
found 1,000 feet higher in elevation.
This is why similar plant life can be found at higher elevations of the
Sandia Mountains as low-elevation places in Canada 4,000 miles north.
There is also a strong relationship
between elevation and temperature. For every 100 meters in elevation the
temperature drops 1°C. This
temperature change is the rate of Adiabatic cooling (Aguado, Edward). When air rises along a
mountain side, pressure decreases and the air expands. Because it is doing work
the air loses energy and cools, making it generally colder at the top of a
mountain than at the bottom. Adiabatic cooling affects the environment of an
area and has an influence on life zones found along mountain elevations.
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| Mechanism of Adiabatic Cooling |
A significant correlation between
elevation and precipitation also exists.
As the elevation increases, the
average precipitation levels also increase. This is because the most common way to cause
condensation in the atmosphere is to cool a parcel of air to its dew
point. Because warm air can hold more
water than cold air, as the air is pushed up the mountain range, it cools
adiabatically and as it cools it gets closer to the dew point, the temperature
at which the moisture in the air saturates.
This causes condensation, cloud formation, and eventually precipitation (Aguado, Edward).
On the other hand, the adiabatic
cooling process causes the area on the leeward side of the mountain to have
little rainfall because, by the time the wind reaches the other side of the
mountain, there is not enough moisture left to precipitate out. Consequently, mountain sides facing away from
the wind receive less moisture. This area directly down-wind of the
mountain is in a rain shadow.
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| Illustration of a Rain Shadow |
A very interesting fact about the Sandia
mountain range: it does not follow the rules of a rain shadow. Contrary to what
one would expect, because these mountains are exposed to such strong sunlight
in the west, even though the prevailing winds come from this direction, the
mountain still has very little moisture on the theoretically “wetter” side. The area that lies in the rain shadow of the
Sandia Mountains actually gets anywhere between 0.94 and 3.02 inches of rain
per month with a yearly average of 17.39 inches of moisture.
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| The Rain Shadow of the Sandia Mountains is Affected by Intense Sun Exposure |
The Sandia Mountains range from 6,200
feet to more than 10,628 feet in elevation. Temperature and precipitation
correlate with elevation so closely that most life zones are found along
elevation lines and include four main life zones: the Spruce Fir life zone, the Mixed Coniferous
zone, the Ponderosa Pine zone, and the Piñon/Juniper zone. All four of these are only one life zone in
the Koeppen system: a Dfb zone.
The Koeppen system is a classification
system that recognizes five major climactic types and minor subgroups in each. The
five types are designated by a capital letter and the minor types by lower case
letters:
|
Letter
|
Description of Classification
|
|
A
|
Tropical Moist Climates: all months have average
temperatures above 18 degrees Celsius
|
|
B
|
Dry Climates: with deficient precipitation during most of
the year
|
|
C
|
Moist Mid-latitude Climates with Mild Winters
|
|
D
|
Moist Mid-Latitude Climates with Cold Winters
|
|
E
|
Polar Climates: with extremely cold winters and summers
|
In the case of the East Mountains, the
main climate classification is a D—a moist, mid-latitude climate with cold
winters—along with an f – signifying it gets precipitation in all seasons—and a
b – indicating a land mass that is further into a continent away from any large
bodies of water.
According to the University of Elmhurst, "Dfb and Dwb climates are immediately
north of hot summer continental climates, generally in the high 40s and low 50s
in latitude in North America and Asia." In this case, because of the elevation
of the mountains even though the East Mountains are not in the latitude range
they qualify as this type of climate (see above correlation between latitude
and climate).
Overall, the Climate of the East Mountains can be classified as a Dfb climate in the Koeppen System even though it does not completely describe the unique mountain environment.
Sources:
Aguado,
Edward, and James E. Burt. Understanding Weather and Climate. Upper Saddle
River, NJ: Pearson Prentice Hall, 2007. Print.
Julyan,
Robert, and Mary Stuever. Field Guide to the Sandia Mountains. Albuquerque:
University of New Mexico, 2005. Print.
Richs,
R. "Koeppen Climate Classification." Elmhurst.edu. Elmhurst College,
2005. Web. 13 Mar. 2014. <http://www.elmhurst.edu/~richs/EC/101/KoppenClimateClassification.pdf>.
Day,
John A. "Clouds." NWS JetStream - Online School for Weather. National
Weather Service, 2008. Web. 13 Mar. 2014. <http://oceanservice.noaa.gov/education/yos/resource/JetStream/synoptic/clouds.htm>.
