LECTURE 14: CLIMATE AND OTHER NICHE AXES Flashcards
Ecological Niche
the combination of physiological tolerances and resources requirements of specific species
- in essence, a species place in the world - the food it eats and the climates in which it lives
Hutchisionian Niche
- an “n-dimensional hypervolume” that shows the distribution of a species with respect to two different environmental gradients
- the dark blue is the optimum value in with the ability of the organism is at its peak
- the lighter blue are regions in which the organism can live
- the white are areas in which the organism cannot live
Scarlet McCaw - Hutchisonian Niche
- Each red dot is an observation of the McCaw with respect to two environmental variables
- Shows that it prefers warm temperatures with relatively moderate amounts of rain
Global Gradients
- Temperature changes with the latitude
- Temperature is lower at higher latitudes (seasonality is a functionality of temperature)
- Temperature is higher at lower latitudes (seasonality is a function of precipitation)
What does rainfall depend on?
- atmospheric circulation
- ocean currents
- rain shadows
The effect of Earth’s tilt on seasons
- Winter in Norther Hemisphere*
- The northern hemisphere is tilted away from the sun; lower angle of incidence, therefore, a greater amount of surface area for the given amount of photons to extend over
- Usually, the sun’s angle of incidence is the largest over the equator so therefore there is greater photon density per unit area and thus it is typically the hottest at the equator or around it
Hadley Cells and Atmospheric Circulation
- Picks up moisture from water masses
- Hot air rises (rises due to low pressure and density)
- Cools as it rises - similar to adiabatic gas flow
- Once at the top of the atmosphere, the air is very moist with a lot of precipitation; a low-pressure zone where precipitation occurs
- Air continues to flow to 30 N or 30 S (depending on the hemisphere) and cool air begins to fall
- Air heats as it falls and the cycle begins again
Other Atmospheric Cells acting like a geared train
- Hadley cells form continuous loops, not always closed loops
- Air can go on to close the Hadley loop or set up the functioning of another set of atmospheric cells - the Ferrel cells
- Ferrel cells extend from 30 degrees to 60 degrees and circulate in the opposite direction of Hadley cells - functions in a similar manner as the Hadley cells do
- Ferrel cells form closed loops but have the potential to set up the activity of another set of less strong cells, polar cells, that effect regions of latitudes between 60 and 90 in either hemisphere
Intertropical Convergence Zone
Area of rain clouds that extends over the pacific ocean
Product of what happens when the two Hadley cells meet
Why does the intertropical convergence zone move?
- Due to the sun not shining directly over the equator because of the tilt of the Earth about its axis
- The activity and distribution of landmasses
- The ITCZ is higher in July than it is in January and this is due to the movement of the sun
- Also expands a wider and more differentiated range throughout the year through Asia because there is a lot of landmasses that causes diversification in these rainy regions
Coriolis effect
- Imposed force on the direction of winds due to the Earth’s tilt about the axis
- winds move east if they are going away from the equator
- winds move west if there are going toward the equator
The direction that atmospheric cells move air and wind?
- Hadley move wind toward the equator
- Ferrell move the wind away from the equator
- Polar move wind toward the equator
Where the sun is shining at different phenomenons during the year?
- The autumn and spring equinoxes are when the sun is shining directly over the equator
- The Summer solstice is when it is shining 23 degrees N
- The winter solstice is when it is shining 23 degrees S
Tropic of Cancer and Capricorn
- Tropic of Cancer: positioned at 23.5 N
Tropic of Capricorn: positions at 23.5 S
Where are the tropics found?
In between the Tropic of Cancer and the Tropic of Capricorn (Between 23.5 N and 23.5 S)
Trade Winds
- prevailing easterlies that are found in between the equator and in both directions up to 30 N and 30 S
- Areas of low pressure
- Caused by the Coriolis effect
Where do you find areas of low pressure?
- Areas of low pressure are found at areas in which there is precipitation (0, 60, 90)
- Areas of high pressure are where the dry hot air is falling and thus is only seen at both 30 N and 30 S
How many atmospheric cells are there?
there are three (Hadley, Ferrel, and Polar) and there are 2 of each along the length of the globe
Which ways do winds circulate in the northern and southern hemispheres?
- Northern: anticlockwise loops
- Southern: clockwise loops
Wandering Albatross
- circumnavigator that is able to travel the radius of the world; prevails in the roaring 40s
Describe Polar Winds
Polar winds move toward the equator of the earth, therefore there are polar easterlies travels toward the west and originating from the east
Doldrums
At the equator, it is an extremely low-pressure zone that is characterized by very weak winds that we refer to as doldrums
Vegetation growth increases with…
Moisture and temperature
We can measure vegetation growth by…
temperature as well as moisture
Where are deserts found?
In extremely high-pressure zones
- Where the Hadley cells bring their dry dense air back to earth
- Found at both 30 N and 30 S
Why are maritime environments more moderate?
Landmasses change temperature more readily than water does
- Oceans provide thermal inertia
What affects where the air is moisture-laden and there is low precipitation
- orogenic precipitation
- prevailing winds
- lots of rain from the warm water and less rain from cold waters
Why is there greater temperature variation in the northern hemisphere?
More landmass and thus continental climates have more variable seasonality and climatic conditions
Ocean currents transport
- warm water from equator toward poles and cold water from poles toward the equator
Gulf Stream
The gulf stream is a stream of warm water from Mexico that inflicts warm climatic conditions onto Great Britain
Orogenic Precipitation
- Air passes rise up on a mountain on the windward side
- as the air rises, it cools and then when it hits the upper atmosphere it falls as rain
- when it falls as rain, its produces a rain shadow on the leeward side of the mountain that is characterized by the lack of vegetation and moisture
Animal geographic ranges often are due to…
biomes
Biome
An ecological community due to shared physical environments; affected by temperature seasonality and rainfall
Ecological niche modeling
Using current climatic data of a species in order to predict its range in the future
How is climate change affecting species distributions?
Since the climate is warming, organisms have been noticeably radiating toward the poles in order to ensure that they maintain their current environmental conditions and fulfill their requirements
