Mountain climate

Mountain Geography, term A, 2007

Major climatic controls

• ALTITUDE

• LATITUDE

• CONTINENTALITY

• TOPOGRAPHY

Climate factors/elements

• 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 windsWarm, dry winds coming offthe leeward side of the mountains

Explain why they occur

Also called Foehn (Germany);Mistral (French Alps)Santa Ana (California)

Monsoon winds

•regional scale wind systems •created by the temperature contrasts between land and ocean •Land heats up/cools faster than oceans

warmer

Direction of themonsoon

Valley breeze (Anabatic) - upslopeDaytime

warmer

LOW P

colderHIGH P

Temperature inversion

Mountain breeze - Katabatic(downslope)

Night time

colder

HIGH P

warmerLOW P

Mountain/Valley breeze

Mountain breathes IN Mountain breathes OUT

IN

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):

• 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