Lesson 3: Climate Flashcards
Global-scale drivers of mountain climates:
What is Weather?
- Weather is the hour to hour and day to day variability in atmospheric conditions.
- This includes temperature, precipitation, humidity, air pressure and wind at any specific location and these conditions can change rapidly.
Global-scale drivers of mountain climates:
What is Climate?
- Climate is the long-term average of weather and its extremes
- Climate is usually generally predictable, as weather is much more variable
Global-scale drivers of mountain climates:
At the Global Scale, what three primary forces regulate mountain climates?
- ) Latitude (distance from the equator)
- ) Elevation (height above sea level)
- ) Continentality (proximity of distance to large water bodies such as oceans)
Global-scale drivers of mountain climates:
Why are temperatures higher near the equator?
- Solar radiation
- The sun’s rays hit the Earth directly concentrating solar radiation. In contrast, at higher latitudes, the sun’s rays hit the earth at an angle (because of its sphere shape) causing the same solar radiation to be spread over a larger area
Global-scale drivers of mountain climates:
What is seasonality? Seasonality is greater or less at higher latitudes?
- How temperatures fluctuate during a year
- Greater
Video:
True or False: The Earth is closer to the Sun during the summer and further away from the sun during the winter…
- False - this is a common misconception. The northern hemisphere is actually closer to the sun during the winter, and further away in the summer.
Global-scale drivers of mountain climates:
What three factors cause seasonality to be greater in higher latitudes?
- ) The tilt of the earth on its axis
- ) The revolution of the earth around the sun
- ) The greater variation in solar radiation
Global-scale drivers of mountain climates:
At what angle, relative to the sun, is the earth tilted on its axis?
- 23.5 degrees
Video:
During summer in the Northern Hemisphere, solar radiation strikes the Earth most directly near the…?
- Tropic of Cancer around the latitude of 23.5 degrees North.
Video:
During summer in the Southern Hemisphere, solar radiation strikes the Earth most directly near the…?
- Tropic of Capricorn around the latitude of 23.5 degrees South.
Global-scale drivers of mountain climates:
What is the main point to remember about temperatures across the earth?
- There is a very predictable temperature imbalance over the surface of our planet created by uneven solar radiation across the latitudes.
- Whichever hemisphere, N or S, is tilted toward the Sun received solar radiation most directly, resulting in higher temperatures.
Global-scale drivers of mountain climates:
What is Atmospheric Circulation?
- Large scale movement of air on the surface of the earth, created by uneven solar radiation across latitudes, that controls global patterns of wind and precipitation
Video:
What is Air Temperature?
- Air temperature is just a measure of how hot or cold the air is
Global-scale drivers of mountain climates:
What is Air Density?
- The compactness of molecules in the air
- Hot air is less dense than cool air because the molecules are moving faster and filling up more space. This causes hot air to float upward, just like hot air balloons.
Global-scale drivers of mountain climates:
What is Atmospheric Pressure?
- The downward force of air in the atmosphere caused by gravity pulling molecules of air towards the air
- Lower air density leads to lower atmospheric pressure, because the more spread out air molecules are, the less force they exert
Global-scale drivers of mountain climates:
What are Pressure Gradients?
- Differences in atmospheric pressure between areas
- Air tends to move along pressure gradients from areas of high pressure to low pressure, forming wind and driving global circulation patterns
Global-scale drivers of mountain climates:
What is the Intertropical Conergence Zone?
- A zone near the equator where high temperatures create an area of low atmospheric pressure
Global-scale drivers of mountain climates:
Lower temps N and S of the equator create areas of high pressure. Following the high-to-low pressure gradient, air flows along the surface of the Earth from higher latitudes toward the equator. At the same time as air moves across the surface of the Earth toward the equator…?
At the same time as air moves across the surface of the Earth toward the equator, warm air that rises near the equator moves toward the poled, forming circulation cells.
Global-scale drivers of mountain climates:
What are Circulation Cells?
- Belts that encircle the earth in which prevailing winds occur
Global-scale drivers of mountain climates:
How many Circulation Cells are there?
- If the earth did not rotate, there would only be two, 1 in each hemisphere. However, since it does rotate, there are three in each hemisphere
Video:
In the Hadley Cell, warm air that rises at the equator and moves poleward sinks towards the ground around…
- 30 degrees latitude, creating high pressure zones. These high pressure zones around 30 degrees cause air to diverge and flow back towards the equator completing the Hadley Cell
Global-scale drivers of mountain climates:
What is the Coriolis Effect?
- The earth deflects winds so they do not flow directly north and south. This is because of the rotation of the earth
Video:
In what direction does the earth rotate?
East to West
Global-scale drivers of mountain climates:
In the northern hemisphere, winds appear to be deflected in which direction?
To the Right
Global-scale drivers of mountain climates:
In the southern hemisphere, winds appear to be deflected in which direction?
To the Left
Global-scale drivers of mountain climates:
What are Trade Winds?
- The winds in the Hadley cell that tend to blow west and towards the equator are called Trade Winds
Global-scale drivers of mountain climates:
What are Westerlies?
- These are prevailing winds at the Midlatitudes, that blow from west towards the east and upwards towards the poles
Global-scale drivers of mountain climates:
What are Easterlies?
- These are prevailing winds at high latitudes, that blow from east towards the west and towards the equator
Global-scale drivers of mountain climates:
What is the Water Cycle?
- The movement of water between the earth’s oceans, atmosphere, and land
Global-scale drivers of mountain climates:
What is Evaporation?
- Conversion of water from its liquid state on the earth to a gaseous state in the air
Global-scale drivers of mountain climates:
What is Condensation?
- At lower temperatures, air molecules move slower causing many of them to convert back into a liquid state in a process called condensation
- The rising of moist, warm air causes areas of low atmospheric pressure to be associated with cloudiness and high levels of precipitation
Video:
Where are the High Pressure zones and what does that mean for climate?
- 30 degrees north and south of the equator
- This means that climates here are more dry and deserts form. The Himalayas and Andes are in High Pressure zones (conversely, Mount Kilimanjaro and Kinabalu are in tropic, low pressure zones)
Global-scale drivers of mountain climates:
As elevation increases, temperature…?
Decreases.
As elevation increases, atmospheric pressure decreases, causing rising parcels of air to expand and cool. Heat is not lost to atmosphere, just spread over greater area.
Global-scale drivers of mountain climates:
Is solar radiation higher or lower at higher elevations?
- Higher
- This means that higher elevations receive more harmful ultraviolet/UV radiation
Global-scale drivers of mountain climates:
Relatively small, isolated mountain peaks have little influence on the temp of the atmosphere. Large mountains that are massed together do influence regional climates, a phenomenon called…?
The mountain mass effect.
Global-scale drivers of mountain climates:
What is Continentality?
- Mountains proximity to large bodies of water such as oceans
Video:
The further inland you are, the more continental your location. True or False?
True
Video:
Where are daily and seasonal temperature differences greater and smaller when comparing coastline mountain ranges to landlocked mountain ranges?
- Greater in landlocked
- Smaller in Coastline
Global-scale drivers of mountain climates:
Water bodies moderate climate by curbing temp extremes because water heats and cools more ___ than land.
Slowly
Global-scale drivers of mountain climates:
Mountains also act as ___ that intercept air masses, forcing them upwards, leading to cloud formation and increasing precipitation relative to low-lying areas.
Barriers.
Global-scale drivers of mountain climates:
What is Orographic Precipitation?
- This is precipitation that occurs when topographic barriers force air to rise, like when mountains intercept air masses, forcing them upward, leading to cloud formation and increasing precipitation in low-lying areas
Global-scale drivers of mountain climates:
Indicate what is greater or less for continental mountains:
1.) Temperature Extremes
2.) Cloudiness
3.) Precipitation
- ) Temperature Extremes - Greater
- ) Cloudiness - Less
- ) Precipitation - Less
Global-scale drivers of mountain climates:
What are the two sides of a mountain called in regards to prevailing winds? Which side has more precipitation?
- ) Windward Side - more precipitation
2. ) Leeward Side - less precipitation, and rain shadow
Global-scale drivers of mountain climates:
Precipitation increases as you move up a mountain because decreasing temps lead to greater condensation. Once the moisture content in the air becomes exhausted…?
Once the moisture content in the air becomes exhausted, clouds begin to break up, causing mountain peaks to be quite dry.
- The potential for mountains to block the spread of marine climates inland depends on their orientation to the prevailing winds.
Videos:
What is a Foehn, and how does it happen?
- Chinook winds, dry warm winds that flow downslope that are caused from air descending on the leeward side of a mountain encountering higher atmospheric pressure and compressing, causing it to warm
Local-scale drivers of mountain climates:
What are local-scale drivers of mountain climates?
- Slope aspect (direction a slope is facing)
- Angle of slope
- Topography (physical features of the landscape)
Local-scale drivers of mountain climates:
When is maximum solar radiation relieved by mountains?
- When they are perpendicular to the sun’s rays
- Ex.) 45 degrees south, maximum solar radiation is received when mountain slopes are at a 45 degree angle relative to the horizontal surface
Local-scale drivers of mountain climates:
What is Temperature Inversion?
- This occurs when there is a valley between two peaks, and the temperatures at the highest peak start to increase as you move downward, but then drastically decrease in the valley, and then increase appropriately as you move up the pass
- This occurs because cold dense air sinks into the valleys and the sun’s rays may never hit those areas if the slopes are very steep (sun mostly controls uppermost slope temps)
- Common in mountains, especially in winter
Local-scale drivers of mountain climates:
What are Microclimates?
- Microclimates are small areas with conditions that differ than those of the surrounding region
- They can be important habitats for many animals and plants that live in mountain environments
What is the Alpine Treeline?
- It is a transitional zone where beyond a certain elevation, environmental constraints prevent tree growth and the dominant vegetation shifts to low statured plants, such as shrubs and herbs and grasses
Video:
What is Flagging?
- Where tree limbs on the windward side of the mountain are unable to survive the high winds, so branches only form in alignment with the prevailing winds
The formation of the alpine treeline is a global phenomenon, primarily caused by temp constraints. What are they?
Trees generally require a min growing season of 3 months during which the mean air temp reaches at least 6 degrees.
Video:
What is the Latitude Influence on Treeline?
- Tree lines on mountains are higher at lower latitudes because they receive greater amounts of solar radiation
At lower elevations, higher trees can more effectively capture light resources, giving them a competitive advantage over short plant growth forms. At high elevations?
At higher elevations, the height of trees becomes a disadvantage. They are exposed to high winds and have little protection from the cold relative to shorter growth forms.
What is the Continentality Influence on Treeline?
- Mountains closer to continental interiors have higher tree lines because:
1.) Less cloud cover means more solar radiation
2.) Mountain mass effect retains heat
(Also better protected from wind)
What are Ecotones?
- They are transitional zones between biomes
The transition zone between forests and alpine tundra is referred to as the… ?
Alpine treeline ecotone
Several factors influence treeline at the local scale. What is the Local Topography Influence on Treeline?
- Snow melt occurring later from accumulated snow in valleys prevents establishment of seedlings, and treeline would be lower
What is an Inverted Treeline?
- In some places, cold air drainage onto valley floors, or inversions, as we discussed earlier, may create inverted treelines
Geography exercise:
Lesson 3?
Mount Kilimanjaro(Tanzania, Africa; hihest in Africa, dormant stratovolcano)
Mount Kinabalu (Borneo, SE Asia; home to 5-6,000 species)
Himalayas (Asia, separating plains of India subcont. from Tibetan Plat., Mount Everest)
Tibetan Plateau (Central and E Asia)
Andes
American Rockies (W US)
Sierra Nevada Mountains (W US; features lake Tahoe)
Australian Alps (SE Australia)
Tech Tip (Matt Peter): What is SPF?
Sun Protection Factor
- SPF 60 means 1/60 UV rays reach the skin
