Log entry: environmental studies: earth science

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Chapter 1 Discovering the Earth’s Dimensions

Visualizing Physical Geography by Timothy Foresman & Alan Strahler

Chapter Overview

The World of Geography

The Shape of the Earth

Global Location

Global Time

Mapping the Earth

Frontiers in Mapping Technologies

What is happening in this photo?

Courtesy of NASA

The World of Physical Geography

Physical geography plays a valuable role in:

Understanding the planet

Addressing issues of sustainability

Population increase

7 billion today

Estimated 10 billion people in 40 years

Integrating the human and physical world

Courtesy of NASA

The World of Physical Geography

The Science of Geography

Geographers study Earth.

Geographers consider:

Spatial considerations (related to physical space)

Temporal considerations (related to changes of time)

1973

2006

USGS, courtesy NASA/Goddard Space Flight Center

The World of Physical Geography

What are some of the spatial and temporal changes between these two photos?

1973

2006

USGS, courtesy NASA/Goddard Space Flight Center

The World of Physical Geography

The five essential themes of geography:

Location

Home address

GPS = Global Positioning System

Place

Region

Human-Earth relationships

Movement

The World of Physical Geography

The Science of Geography:

Physical Geography

Study of the Earth’s living and nonliving systems

Study of landscapes, and natural processes such as weather, climate, and geology

Human Geography

Study of spatial interactions and patterns related to human activity such as social, cultural, and economic topics

The World of Physical Geography

The Science of Geography:

Technology, Tools, and Quantitative Methods

Cartography

GIS = Geographical Information Systems

Remote Sensing

Statistics

The World of Physical Geography

The World of Systems

Constant Interactions of energy and material between the Earth’s four major systems:

Atmosphere

Hydrosphere

Lithosphere

Biosphere

The World of Physical Geography

Methods and Tools for Geography

Eratosthenes

No shadow on summer solstice in Aswan

Earth’s size

Today’s technology

Remote sensing

GIS

GPS

Internet

Web-based mapping tools

Methods

Scientific method

Courtesy NASA

The World of Physical Geography

Methods and Tools for Geography

Scientific method = the formal process that a scientist uses to solve a problem, which involves first observing and formulating a hypothesis and then testing and evaluating results

Hypothesis = logical explanation for a process or phenomenon that allows prediction and testing by experiment

The World of Physical Geography

Methods and Tools for Geography

Steps of the Scientific Method

Generate critical inquiry from investigations and field observation.

Formalize questions into a testable hypothesis to explain observations.

Select method(s) of analysis and control for variables and conditions for experiment.

Collect data for controlled experiment.

Conduct experiments to test hypothesis.

Reject or accept the hypothesis.

Document results, provide new scientific facts, and apply them to support theory or greater understanding.

The World of Physical Geography

Geographic Use of the Scientific Method

Step 1: Observe a spatial pattern of vegetative growth that is different on the west side of each of the Hawaiian Islands than on the east side.

Step 2: Formalize a hypothesis:

Hypothesis 1 = Vegetation patterns are explained by rock type.

Hypothesis 2 = Vegetation patterns are explained by temperatures.

Hypothesis 3 = Vegetation patterns are explained by rainfall.

The World of Physical Geography

Geographic Use of the Scientific Method

Step 3: Select method of analysis. Use the big island of Hawaii to map the specific 16 × 16 km (10 × 10 mi) square test areas on the west and east sides of the island.

Step 4: Collect data:

Vegetation maps from NASA satellites

Geologic maps from USGS

Temperature data from NOAA

Collect rainfall data from NOAA services

The World of Physical Geography

Geographic Use of the Scientific Method

Step 5: Conduct experiments to test hypothesis:

Overlay rock type on the vegetation map to look for patterns.

Look for correlation between rock type and vegetation within grids.

If hypothesis rejected, return to this step to test next hypothesis.

Step 6: Reject or accept hypothesis:

No correlation between rock type and temperature with vegetation.

Positive correlation between rainfall and vegetation.

The World of Physical Geography

Geographic Use of the Scientific Method

Step 7: Document results and apply to theory:

Documentation allows others to review for verification.

If sufficient more tests conducted on other islands, the hypothesis may be elevated to a theory.

Theory = a hypothesis that has been tested and is strongly supported by experimentation, observation, and scientific evidence.

The World of Physical Geography

Geographic Use of the Scientific Method

Courtesy NASA

The World of Physical Geography

Geographic Use of the Scientific Method

Courtesy NASA

The World of Physical Geography

Geographic Use of the Scientific Method

Courtesy NASA

The World of Physical Geography

Geographic Use of the Scientific Method

Courtesy NASA

The World of Physical Geography

Geographic Use of the Scientific Method

Courtesy NASA

Is the Earth round?

The Shape of the Earth

Courtesy NG Image Collection

Courtesy NASA

The Earth is not a perfect sphere:

Equatorial diameter slightly greater than polar diameter

Poles = the two points on the Earth’s surface where the axis of rotation emerges

Axis = an imaginary straight line through the center of the Earth around which the Earth rotates

The Shape of the Earth

Global Location

Geographic Grid

Network of parallels and meridians used to fix location on the Earth

Meridian = north-south line on the Earth’s surface, connecting the poles

Parallels = east-west circle on the Earth’s surface, lying on a plane parallel to the equator

Global Location

Geographic Grid

Equator is parallel of latitude lying midway between the Earth’s poles; it is designated latitude 0º.

Intersection of meridians and parallels makes up the geographic grid.

Global Location

Geographic Grid

Latitude

An angular distance for a point north or south of the equator, as measured from the Earth’s center

Like “ladders”

Equator (0o) divides northern and southern hemisphere

Global Location

Geographic Grid

Longitude

The angular distance for a point east or west of the prime meridian. (Greenwich), as measured from the Earth’s center.

Prime meridian is 0o.

Longitude measured eastward or westward from the prime meridian from 0o to 180o.

Global Location

Longitude

Prime meridian runs through Greenwich, England.

If we are facing north, which side is to the east?

What is the latitude and longitude of Point P?

Global Time

Earth’s geographic grid and the rotation of the Earth help define global time.

Solar Time

Based on Earth’s rotation

Makes one full turn in a day (24 hours)

Sun rises in the east and sets in the west

Solar noon = reaches its highest angle

Solar timekeeping

Global Time

Solar Time

Sun only shines on half of Earth at one time.

Shines on eastern sides first.

Local time is determined primarily by longitude.

When it is noon in Chicago, is it earlier or later in:

a. Portland? b. New York?

Standard Time

Designated 24 standard meridians around the globe, at equal intervals from the prime meridian.

Global Time

Time Zones of the World

Coordinated universal time (UTC)

Bottom figure labels = number of hours of difference between that zone and Greenwich mean time

A negative 7 = seven hours behind Greenwich time

A positive 3 = three hours ahead of Greenwich time

Global Time

Time Zones of the World

Global Time

Time Zones of the Conterminous United States

Eastern, Central, Mountain, and Pacific

Daylight saving time = clocks set ahead (spring forward)

If it is 3:00 pm in New York City, what time is it in:

a. Atlanta?

b. Dallas?

c. Los Angeles?

Global Time

The International Dateline (IDL)

Follows 180th meridian except through the Aleutian Islands, Alaska and island nation of Kiribati

Move east across IDL, subtract a day

If you flew from Los Angeles to Beijing, would you add or subtract a day?

Global Time

Time Zones of the World

If it is 7 am Sunday, in New York, NY, what day and time is it in Tokyo, Japan?

Mapping the Earth

Map = a graphic, scaled representative view of the Earth, or any portion of the Earth, as viewed from above, depicting various features of interest.

Cartography

Subfield of geography

Representing Earth through maps

Mapping the Earth

Map scale = the relationship between distance on a map and distance on the ground, given as a fraction or a ratio.

Three types of map scale:

Verbal scale, such as 1 cm = 1 km

Representative fraction

1:50,000 means that 1 unit of map distance equals 50,000 units on the Earth

1 cm on the map equals 50,000 cm or 500 m or 0.5 km on the ground

Graphic scale

Shows scale on a bar

Stays accurate if map size changes

Mapping the Earth

Map Scale

Map Projection

A system of parallels and meridians represents the Earth’s curved surface drawn on a flat surface.

Curved surface cannot be projected onto a flat sheet without distortion.

Four main types

of projections:

Cylindrical

Conic

Plane

Elliptical (oval)

Mapping the Earth

Cylindrical Projection

Wraps a cylinder around the globe so that the paper touches the globe at the equator.

Parallels increases at higher latitude so that the spacing at 60°is double that at the equator, which distorts landmasses, as seen with Greenland.

Example: Mercator project

Mapping the Earth

Plane Projection

Produced by projecting a map from a center lit globe onto a piece of paper touching the globe at any point.

Can choose any center point, from which directions and distances are true, but in outer areas, shapes and sizes are distorted.

Mapping the Earth

Conic Projection

Cone sits atop the globe like a cap, with the point of the cone typically situated over one of the poles.

Accuracy is greatest along the circle it touches—the standard parallel.

Good format for mapping mid-latitude regions that are larger east to west than north to south.

Mapping the Earth

Elliptical (Oval) Projection

Central meridian and all parallels are straight lines, with relative sizes represented accurately, but shapes are distorted at the edges.

Often used for thematic or political maps.

Example: Mollweide equal area map

Mapping the Earth

Distortions in Map Projections

All maps are distorted.

Mapmaker decides whether to preserve shape, size, or a compromise.

Conformity

True shape map preserves shape but distorts size.

Example: Mercator projection

Great Circle Route is the shortest distance between two points.

Mapping the Earth

Distortions in Map Projections

Equivalence: Equal-area projection

Preserves size but distorts shape.

Example: Goode’s projection

Mapping the Earth

Distortions in Map Projections

Compromises

Sacrifice equivalency and conformity for the sake of portraying a general balance between the two

Example: Winkel Tripel projection

Frontiers in Mapping Technologies

Remote-Sensing Tools

Use of technology to record observations from a distance (e.g., aerial images)

Handheld, aircraft, and satellites capture radio waves, microwaves, infrared energy, and visible wavelengths.

Used for a variety of environmental and land-use issues

Population and land use change in Las Vegas between 1973 and 2006.

Frontiers in Mapping Technologies

Remote-Sensing Tools

Spatial resolution = size of the smallest area, or pixel

Spectral resolution = range of wavelengths captured by the sensors

Important Earth Observing System (EOS) satellites:

Landsat

Weather satellites for ozone, temperature, clouds

Terra

Courtesy of NASA

Frontiers in Mapping Technologies

Geographical Information Systems (GIS)

A combination of software, data, and operational organization

Provides the capacity to capture and communicate spatial relationships among geographic features, values, and objects in digital databases

Frontiers in Mapping Technologies

Geographical Information Systems (GIS)

A useful analysis tool

Designed to answer questions with spatial information:

What is the best route to deliver packages?

Which wells will be polluted by underground aquifer contamination?

What property values will suffer from loan defaults in one neighborhood as compared to another?

Frontiers in Mapping Technologies

Geographical Information Systems (GIS)

Geocoding: These questions are answered by merging conventional data with their geographic locations.

GIS maps are common feature in public hearings.

Frontiers in Mapping Technologies

Global Positioning Systems (GPS)

Accurately determines geographic location

Consists of 24+ satellites that orbit Earth

Receivers work by measuring and triangulating time delay of signals from a minimum of three (usually four or more) GPS satellites.

Handheld devices and phones automatically enable GPS data to be recorded.

openstreetmap.org

Represents a creative approach to citizen-led data collection for mapping world’s streets

Available for free

Frontiers in Mapping Technologies

Geobrowsers and 3-D Mapping

Internet mapping

Uses:

Reporting on humanitarian issues

Tracking eco-disasters

1. What does a geographer see?

2. If the resolution of Blue Marble is 1 square kilometer, how can geographers keep track of 8.5 million points to discern changes in land use?

Courtesy NASA

Frontiers in Mapping Technologies

Geobrowsers and 3-D Mapping

Computer programs that access and query geographic data draped over a computer-generated globe

Google Earth

1. Explain how space-age technologies have affected the field

of geography.

2. What do you think we can expect from these technologies in the future?

Courtesy NASA