SPATIAL SCALES IN PHYSICAL GEOGRAPHY

Physical processes behave at various scales

1. Global2. Continental3. Regional4. Local5. Individual

SCALES IN PHYSICAL GEOGRAPHY

The research process in Physical Geography (data, methodology, techniques, analysis) depends on the scale (spatial or temporal)

SPATIAL SCALES IN PHYSICAL GEOGRAPHY

Global

Continental

Regional

Local Individual

Sao Paulo: 238 mm in January

TEMPORAL SCALES IN PHYSICAL GEOGRAPHY (TIME CYCLES)

• Daily• Monthly• Seasonally• Annual• Hundreds years• Tens –hundreds of thousands years• Millions of years

DAILY:

SST Anomaly March 2005

MONTHLY:

SEASONAL: ANNUAL: HUNDRED YEARS:

THOUSANDS YEARS: MILLIONS YEARS:

Pangea (~225 million years ago)

SYSTEMS IN PHYSICAL GEOGRAPHY

1. Open flow systems: inputs and outputs of energy and matter

2. Closed flow systems: NO inputs or outputs

Natural Flow systemA system in which energy/matter move trough time from one location to another.Ex: • Flow of energy from Sun to Earth (energy)•River system (matter)

A system is a set of relationships between features, processes or phenomenaRead: Strahler, Chapter2 (Systems in Physical Geography)

SYSTEMSA system is a set of relationships between features, processes or phenomena linked by flows of energy and matter.

Read: Strahler, Chapter 2 (Systems in Physical Geography)

Ex: Hydrologic cycle

1. Open systems: inputs and outputs of energy and matter.

Ex: the river system

OPEN AND CLOSED SYSTEMS

precipitation

river system

INPUT

OUTPUTdischarge to ocean

OPEN AND CLOSED SYSTEMS

2. Closed systems: NO inputs or outputs. The flowing energy and matter move endlessly. Ex: the hydrologic cycle

SYSTEM FEEDBACK

When flow (of matter or energy) in one pathway acts either to reduce or increase the flow in another pathway, reinforcing or reducing the initial flow.

Initial condition (matter/energy)

causes

changes inAnother variables

causes changes in

Initial condition MODIFIED(matter/energy)

FEEDBACK

If the flow is reinforced. There is an increased response in the system.This feedback can create instability, disruption.

Wildfire shrubs and wood dried

More fuel available

MORE fire

POSITIVE FEEDBACK

If the flow is reduced. Further production in the system decreases the growth in the system.This feedback causes a self-regulation in a natural system, stabilizing the system

NEGATIVE FEEDBACK

Warmer Earth

More evaporation

More cloud formation

LESS warmingMore reflectionof sunlight

SYSTEM EQUILIBRIUM

The flow rates in the pathways of a system remain about the same. The amounts of energy and matter within the system are constant.

VEGETATION REMOVED (overgrazing)

TRANSPIRATION?

RAINFALL ?Less or more VEGETATION?

Example: Positive or negative FEEDBACK?

WHY ARE MAPS IMPORTANT ?

•To place locations

Maps are one of the most important tools in Geography.They help us:

• To visualize the “spherical” world on which we live

•To represent physical or human features (at different scales)

Global

Continental

Regional

Ex: Physical features (precipitation distribution)

GlobalContinental

Regional

Ex: Human features (population density)

Ex: El Niño-Southern Oscillation (ENSO) impacts

IMPORTANT CONCEPTS

•Geographic Grid•Latitude •Longitude•Principal lines (Equator, Prime meridian)• Map projections

GEOGRAPHIC GRID

usually given in degrees (°)

Provides a system for locating places on the Earth’s surface

LATITUDE(parallels)

•Define any location on Earth’s surface in terms of how far north or south it is from the Equator (0° latitude)

•Tells us if we are in the Northern or Southern Hemisphere (standard notation: 30° N, 55°S, max lat is 90°)

•1° latitude = 111 km

•Equator is a Great Circle. All the other parallels are small circles

LONGITUDE(meridians)

•Define any location on Earth’s surface in terms of how far it is from the Prime Meridian (0° line of longitude)

•Tells us if we are in the Western or Eastern Hemisphere (standard notation: 100° W, 15°E, max lon is 180°)

•All meridians are half circles (unlike parallels)

•1° longitude =111 km ONLY at the Equator (unlike latitude)

Together, latitude and longitude represent the location of any point on the earth’s surface

A

B

C

Locate the following points and identify the principal physical feature

•Lat: 40°N , Lon: 5°W •Lat: 15°N, Lon: 5°W •Lat: 10°S, Lon: 50°W •Lat: 40°N, Lon: 50°E •Lat: 20° N, Lon: 45°E •Lat: 30° S, Lon: 120°E

EXERCISE

PRINCIPAL LINES

Prime Meridian

Equator

Tropic of Cancer

Tropic of Capricorn

CONTOUR MAPSA contour map is a map of isolinesIsoline: A line which connects points of equal value of a variable (temperature, precipitation, elevation , etc)

Isotherms

Isohyets

CONTOUR LINES INTERPRETATION (CLIMATE VARIABLE)

• Closely spaced contour lines represent a large gradient, widely spaced lines indicate small gradient

Gradient: the rate by which a variable changes spatially

• Concentric circles of contour lines indicate a maximum or minimum value

•Region with highest temperature?•Region with lowest temperature•Region with highest pressure gradient?•Region with lowest pressure gradient?•Region with strongest wind?•Region with lowest wind speed?•Regions with rainfall probability? (low pressure centers)