Transcript Pressure - University of Colorado Boulder

Mountain climate
Mountain Geography, term A, 2007
Major climatic controls
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ALTITUDE
LATITUDE
CONTINENTALITY
TOPOGRAPHY
Climate factors/elements
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Pressure, oxygen, water vapour
Temperature
Precipitation
Winds
Radiation
clouds
3. CONTINENTALITY
4. TOPOGRAPHY
• Barrier effects
– DAMMING
– DEFLECTION
– BLOCKING
• Depends on topography (mtn. range vs.
isolated peak)
Pressure
Temperature
• a measure of the
average kinetic
energy of the
molecules in that
substance.
• how fast the air
molecules are
moving.
Effect of altitude on temperature
Wind
• Wind results from a horizontal difference in
air pressure
• sun heats different parts of the Earth
differently, causing pressure differences
• Sun is the driving force for most winds.
Wind direction
Winds are directed towards low
pressure, which results in:
Lifting of air
"Bad" Weather
Winds are directed away from
high pressure, which results in:
Sinking of air
"Good" Weather
Types of winds
• Large-scale
– Standing waves
– roters
• Regional scale
– Chinook winds;
– Monsoon winds
• Small scale:
– Slope winds
– Mountain/Valley winds
– Glacier wind
Large-scale standing waves
Rotor clouds
Lenticular clouds
Orographic precipitation
• occurs where mountains and hills force
moist air to rise
Chinook winds
Warm, dry winds coming off
the leeward side of the mountains
Explain why they occur
Also called Foehn (Germany);
Mistral (French Alps)
Santa Ana (California)
Monsoon winds
warmer
•regional scale wind systems
•created by the temperature contrasts between land and ocean
•Land heats up/cools faster than oceans
Direction of the
monsoon
Valley breeze (Anabatic) - upslope
Daytime
warmer
LOW P
Temperature
inversion
colder
HIGH P
Mountain breeze - Katabatic
(downslope)
Night time
colder
HIGH P
warmer
LOW P
Mountain/Valley breeze
OUT
IN
Mountain breathes IN
Mountain breathes OUT
Glacier winds
Cloud Formation
In order to make a cloud we need:
• Moisture
• Nuclei on which to condense (cloud
condensation nuclei, or ice nuclei)
• A method of cooling the air to saturation
What about if the air temperature is
below 0°C?
• It is possible for liquid water to remain
liquid below temperatures of 0°C if there
are no Ice Nuclei (IN).
• Liquid water below 0°C is called
"supercooled" or "subcooled" water.
Types of clouds
Need:
Plenty of moisture.
A mass of warm unstable air.
A source of energy to lift the warm,
moist air mass rapidly upward.
Cumulo-nimbus clouds
Home exercise (X-credit):
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Watch for clouds over the Boulder area
Take a picture, identify the clouds
Write about how the clouds was formed
Submit to Abby
Composition of Solar Radiation