Topic 2: MODEL OF EARTH

Topic 2: Model of Earth Model- something that represents the properties or characteristics of something else. Ex: Scale- the ratio between the size of the model and the actual object.

Evidence For Shape of Earth Ships mast example. Altitude of polaris Lunar Eclipse *Pictures from space * Best form of evidence

Earths’ Shape True Shape Oblate Spheroid “Slightly Squatty” Equatorial diameter is greater than the polar diameter. DIAGRAM Apparent Shape “Perfect sphere” Models, pictures from space, scaled drawings

EARTH COMPONENTS Atmosphere- Thin layer of gases that surrounds Earth *!* See pages 1 & 14 in Reference Tables Hydrosphere- liquid water portion of Earths’ surface. 71% of Earths’ surface is covered by water. Lithosphere- solid outer portion of Earth. *!* See pages 1 & 10 in Reference Tables

ESRT Page 14

Finding Location Coordinate system- grid system of lines for determining location. Examples:

Latitude and Longitude Angular distance north or south of the equator. Maximum latitude=90o Latitude = altitude of Polaris! Longitude Angular distance East or west of the Prime Meridian Maximum longitude =180o Longitude is calculated using the difference in local solar time and time at the prime meridian.

Finding Longitude: Example: An observer measures the local solar time as 3 pm. The time at the prime meridian is noon. What is the observers longitude?

Practice What is the Latitude and Longitude of the southern-most point of Australia? What Continent is found at 40oS and 60oW?

Altitude of Polaris: Diagram:

Practice If the time at the Prime Meridian is 4pm and Local Solar Time is 12 noon, what is the observers longitude?

Practice: What would the approximate altitude of Polaris be for an observer located in Watertown New York?

Practice: What city in New York State is located at 43o 5’ N and 79o 0’W?

TIME ZONES

Field Mapping Field- any area that has a measurable value of a given quantity at every point. Examples: temperature, magnetic, gravitational, elevation. Isolines- lines that connect points of equal field value.

Rules for Drawing Isolines: Never cross or touch. (why?) Tend to run parallel Must end at the edge of the map or form a loop “Smooth Curves”

Contour Lines

Isotherms

Isobars

Types of Isolines: Isotherms- Isobars- Contour lines-

Interval- difference in field value between isolines. Ex: Gradient = Change in Field Value Distance

Contour Mapping Topographic map- Used to show the topography (shape) of the land. Lines connect points of equal elevation. Ex: !*! See page 24 in the Review Book

Rules for Topo Maps The closer the contour lines the steeper the slope. Ex:

The V’s in the contour lines that form where they cross a stream point in the opposite direction that the stream flows. Ex:

Hachures are used to show depressions in the topography. Ex:

PROFILES:

In what direction does Maple Stream flow?