Mountains
SPI 0507.8.2 Explain how
mountains affect weather and
climate.
Three Ways
In this PowerPoint you are going to study
three ways mountains affect climate.
– Elevation
– Rain Shadows
– Mountain and Valley Breezes
How Mountains Affect
Weather & Climate
Number 1 - Elevation
Have you ever noticed as you are driving
into Mountain City from Bristol or Johnson
City that the temperatures get cooler?
Johnson County
How many times have you seen snow on
the top of Snake Mountain when there was
none in Mountain City?
The reason for this is the elevation.
Mountain City has the highest elevation of
any city in Tennessee at 2350 feet above
sea level. The highest point in Johnson
County is Snake Mountain at an elevation
of 5574 feet above sea level.
Elevation
• The higher the elevation, the lower the
temperature becomes.
• The rate at which the temperature drops is
known as the lapse rate. On average, the
lapse rate is 3.6 degrees per 1,000 feet.
Elevation Differences
• With Snake Mountain over 2000 feet
higher in elevation than Mountain City, the
temperature on top of Snake Mountain
could easily be 7 degrees cooler.
How Mountains Affect
Weather & Climate
Number 2 - Rain Shadows
Rain Shadows
Mountains greatly affect the climate. They act
as barriers blocking rain and wind.
One side of the mountain may have a very
different climate from the other side. In
some cases mountains create a shadow.
This is where rain does not fall. Deserts
can form in the rain shadow regions.
Animations
• http://www.mhhe.com/biosci/genbio/tlw3/e
Bridge/Chp29/animations/ch29/rain_shado
w_formation.swf
• http://bio1100b.nicerweb.com/med/Vid/Dis
cover2e/ch39a04_RainShadow.swf
• http://www.uky.edu/AS/Geology/howell/go
odies/elearning/module07swf.swf
• http://www.mrphome.net/mrp/rainshadow.s
wf
Example – Rain Shadow
Death Valley in the United States is behind
the Pacific Coast Ranges of California and
the Sierra Nevada range.
BrainPop
• http://www.brainpop.com/science/earthsyst
em/mountains/
How Mountains Affect
Weather & Climate
Number 3 –
Mountain Breezes and Valley Breezes
Mountain Breeze –Valley Breeze
Mountain and valley breezes are very similar
to land and sea breezes.
Remember – Air pressures try to equalize
themselves through wind. High pressures
move toward low pressures.
During the day the surface of the mountain heats the air
high up in the atmosphere quicker than the valley floor
can. This creates a low pressure area near the top of
the mountain. Wind moves from the valley where the
air pressure is high to equalize this pressure.
Day – Valley Breeze
When the wind moves from the valley to the
top of the mountain, this is called a valley
breeze.
During the night the mountain tops
cool more quickly than the air in the
valleys. This creates a high
pressure area at the mountain top
where the air becomes more
densely packed.
The wind changes direction and moves from
the mountain top to the valley floor to
equalize this high pressure.
Mountain Breeze –Valley Breeze
Most of the time we see valley breezes
during the day, as winds blow from the
valley up towards the mountains. During
the night we see mountain breezes, as
winds travel from the mountains, down
towards the valleys.
Animation
• http://www.bborucki.com/wind.swf