 |
| http://www.bing.com/images/search?q=rain+at+the+grand+canyon&view=detail&id=58574A7D0ED9C88EC39A207A3AB22CCC914DFDF7 |
 |
| http://www.bing.com/images/search?q=thunderstorms+at+the+grand+canyon&view=detail&id=7AC3645052D9A0BDD5D7C31585EAA6B3BEB6E05D |
http://www.bing.com/images/search?q=snowfall+at+the+grand+canyon&view=detail&id=645F910CAE493C543F4699CD42DA6A70309DFD3F
The North Rim of the canyon has experienced temperatures of
-22 °F,
while the south Rim of the canyon has experienced 120°F on several occasions. Along
with temperature, precipitation around the canyon varies widely. The North Rim
of the canyon averages 25.8” of rain a year, while the South Rim has areas that
receive less than 1” of moisture a year. Precipitation depends on cloud
formation and the production of rain through a series of atmospheric conditions
and adiabatic processes. These processes
along with the wide range of precipitation occur because air masses in the atmosphere
exist under different conditions. Air masses exist as stable, unstable, or in
between in conditional stability.
http://www.paragonair.com/public/docs/AdvCircs/AC00-06A_AvWx/AC00-6A_ch06.html
Notice
in this picture, the stable air mass is resisting vertical movement, while the
unstable air is rising. Unstable air will rise in the presence and subsequent removal
of force. Conditional stability happens when the air mass is neither stable nor
unstable. This air mass will behave stable, but can change to unstable when
force is applied.
Air masses rise when warm, but begin to descend once cool. The high temperatures found at the canyon allow for warm air parcels to exist and rise. Depending on the condition of the air mass itself, the air parcels may rise leading to changes in temperature and cloud formation.
In this picture, the red denotes warm air. Notice
how the warm air rises. If the Dew Point (100%relative humidity ) is reached, clouds
begin to form and can return what once left as warm air and water vapor, as
moisture and cool air back to the ground. http://www.vivoscuola.it/us/rsigpp3202/umidita/lezioni/form.htm
The above picture depicts orographic lifting and the
rainshadow effect. In the above picture, the air mass encounters a barrier that
pushes the air upward along what is called the windward side. The air is moved
high enough for condensation to occur bringing about precipitation. As the air
begins to descend onto the leeward side of the mountain, all the precipitation has
been left behind on the windward side. This leaves nothing but dry warm descending
air. This process creates the driest of the areas around the canyon as shown in
the following picture.
Sources
http://blackboard.cuonline.edu/webapps/portal/frameset.jsp?tab_tab_group_id=_2_1&url=%2Fwebapps%2Fblackboard%2Fexecute%2Flauncher%3Ftype%3DCourse%26id%3D_70686848_1%26url%3D
