Example of a physical geography problem
The global carbon cycle and climate – human actions such as burning of fossil fuels and
deforestation result in carbon dioxide inputs to the atmosphere, where it acts as a greenhouse
gas, causing harmful climatic changes.
Therefore, this is an example of processes that occur at the interface of human activities,
the atmosphere and the biosphere and its study belongs to the domain of Physical Geography.
A Simple Model of the Earth System – The Four Great Realms
Lithosphere - All processes associated with the solid earth
Hydrosphere - All processes associated with water
Atmosphere - All processes associated with the gases that envelope the earth
Biosphere - All processes that involve living organisms
System Interactions and Dynamics
When interactions between subsystems exactly balance one another (what comes in goes
out) Example – Thermostat
When interactions aren’t exactly balanced at one point in time, but balance out over a long
time Example – Surface Temperature
Changes in the system that lead to further changes in the system
When changes in the system lead to additional changes that re-enforce the initial change
Example - Credit Cards
When changes in the system lead to additional changes that dampen the initial change
Example – Students Attitude and Classroom Ambience
Positive Feedback: Ice-Albedo Feedback
More snow cover
Less energy absorbed from the sun
Less snow cover
More energy absorbed from the sun
Space and Time Scales
Global – Long term climate changes
Continental – El Nino Southern Oscillation (ENSO)
Regional – Geographic shifts in climate regimes (e.g. dust bowl
of the 1930’s)
Local – Extreme events (e.g., short duration droughts;
Short – Atmospheric disturbances (hourly to weekly)
Seasonal – Land vegetation
Interannual - ENSO
Decadal – Solar influences
Long scale – Ocean related
Very very long scale – distribution of continents
Large scale fluctuations in the atmosphere from
hour-to-hour or day-to-day
Weather systems arise mainly due to atmospheric
instabilities, the evolution of which is governed
by non-linear chaotic dynamics.
That is why weather is not really predictable
beyond a week or two into the future.
Super Typhoon Lupit (26W) west of the
Philippine Islands (Nov-26-2003) as seen
by the NASA’s MODIS satellite sensor.
Climate is defined as averaged weather, typically defined in terms of mean and other statistical
quantities (higher order moments), that measure variability over a period of time and over a
geographical region (space).
Climate = What you expect,
Weather = What you get.