Transcript Physical Setting

Geographic Template
• Environmental variables exhibit nonrandom patterns
• Patterns of spatial variation comprise the
geographic template, forms the foundation
of all biogeographic patterns
• Biota and interactions of biota form
gradients in response to geographic
template
Geographic Template
• Energy driving spatial and temporal
dynamics
– Earth’s core and gravity
– Sun – heat transfer, angle and seasons
Local to Global Effects
(S-facing slopes in N.
Hemisphere (opp in S. Hem.
Elevational Effects
• Why glaciers at tropics?
• Properties of Air
• Density and pressure of air decreases with
elevation
• Air moving up a mountain loses heat due to
reducing density
• Loses heat energy (adiabatic cooling) as
molecules move apart
Greenhouse Effect
• Water vapor and carbon dioxide (as well as
methylated metals) trap longer energy
wavelengths
• Holds heat
• Moist environments – limited diel temp
fluctuation
• Dry environments – diel temp flux
Wind and Rainfall
• Climatic cells –
differential heating
• Coriolis effect –
wind patterns
• Surface winds
create ocean
currents
• Temperature + Winds + Ocean Currents = global
pattern of precipitation
•Predictable general trends
•Rainy season in tropics tied to equinox
•Horse latitudes (30 – 35° N and S) –
descending air absorbs moisture
•Mediterranean climate – west side of
continents – hot, dry summer; mild, wet
winter
Rain Shadow
Climate and Scale
• Climate scales down to millimeters
• Creates patchy distribution
• Inhospitable environment can contain
hospitable meso- and microclimates
Soils
• Distinct pedogenic regimes
• Close correlation with global climate cycles
(compare Figures 3.7 and 3.12)
• Soil types can range from limited (Great
Plains) to complex mosaic (mountains)
• Tell story of temporal development of global
geographic template (and a time-travelling
map)
Aquatic Environments
• Main points to get are diversity of space and
time
• Patchiness (clinal zones in lakes, intertidal
to abyssal in oceans)