Cornell NotesCh. 3 Models of the Earth

Models

• Models are representations of real objects or systems– Allow us to manipulate things that we can’t work with in

real life.– Allows us to predict what would happen under different

conditions or in the future.• Physical models= a 3 dimensional representation used to

show relationships between parts.– Model solar system

• Conceptual models= a diagram that shows how the parts of a larger whole are related.– Food web

• Mathematical models =based on mathematical equations.– Population next year=(This year’s population+ all births+all people

moving in)-(all deaths+all people moving out).

What types of models do we make of the Earth?

• Globes are physical models that represent the Earth’s surface.

• A map is a flat representation of the curved surface of the Earth.– A conceptual model of the Earth’s surface.

Cartography

• Cartography is the science of map making.• Cartographers are scientist who make maps.– Collect data from a lot of sources• Surveys• Remote sensing—the process of gathering and

analyzing information about an object without being able to physically touch it.

Satellite Image of Las Vegas

How do we make maps?

• The problem is that it is hard to transfer a curved surface to a flat format.

• Map projections –a flat map that represents the curved surface of the earth.

• Distortions always happen in map projections.

Types of Map Projections

1. Cylindrical• Created by placing a

screen around the globe in a cylinder shape.

• most common type of map that we see.

• areas close to the equator have very little distortion.

• the closer to the poles that one travels, the more distorted the map becomes.

• In this example, Greenland appears to be many times larger than it really is because it is close to the poles.

2. Conic• created by placing a

cone shaped screen on a globe.

• more accurate than the cylindrical projection map

• further we travel down the map, the more distorted and less accurate the map becomes.

3. Planar/Azimuthal• Created by

placing an imaginary screen directly above or below a globe

• This type of map projection is not commonly used.

4. Robinson Projection• Created when a screen is cut and wrapped

around a globe, like wrapping a round present.• Little distortion of continent size or shape

What are maps used for?

• There are all sorts of maps. Here are a few.Road mapsWeather mapsSatellite mapsGeologic mapsSoil mapsTopographic maps.

Road maps

Weather maps

Satellite maps

Geologic maps