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Models of the Earth - PowerPoint PPT Presentation

Models of the Earth. Earth. Very nearly perfect sphere No top, bottom or sides Earth’s axis of rotation can be used to establish reference points Reference points: North and South poles Equator divides earth into northern and southern hemisphere. Latitude. Parallels-

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Models of the Earth

• Very nearly perfect sphere

• No top, bottom or sides

• Earth’s axis of rotation can be used to establish reference points

• Reference points:

• North and South poles

• Equator divides earth into northern and southern hemisphere

• Parallels-

• describes north and south of the equator

• Run east-west parallel of the equator

• Latitude

• Angular north or south of the equator

• Measured in degrees

• Equator is 0°

• North Pole and South Pole is 90°

• Each degree consists of 60 equal parts called minutes

• 1.85 km

• Symbol is ‘

• Each minute is divided into 60 equal parts called seconds

• Symbol is ‘’

• Meridian

• is a semicircle that runs from pole to pole

• Prime meridian is 0°

• Longitude-

• is the angular distance east or west of the prime meridian

• All locations have a longitude between 0° and 180° east or west of the prime meridian

• A degree of longitude equals approximately 111 km

• Decreases as you move towards the pole

• Any circle that divides the glove into halves or marks the circumference of the globe

• Any circle formed by two meridians of longitude that are directly across the globe from each other is a great circle

• Can run in any direction around the globe

• Air and sea routes often follow great circles

• Use a magnetic compass

• Geomagnetic poles- areas of earth’s surface above where the poles of the imaginary magnet

• Needles of compass points to geomagnetic north pole

• Angle between the direction of the geographic pole and the direction in which the compass needle points is called magnetic declination.

• Measured in degrees east or west of the geographic north pole

• GPS can be used to find their location on earth

• Based on a global network of 24 satellites that transmit radio signals to Earth’s surface.

• First one was NAVSTAR (launched in 1978)

• Can be accurate within 10-15 meters of position

Mapping Earth’s Surface

• Globe- model of earth

• Accurately represent locations, relative areas, and relative shapes

• Useful for large surface features

• Too small to show details of earth’s surface

• Cartography

• Scientists who make maps

• Collect data by a field survey or remote sensing

• Remote sensing

• The process of gathering and analyzing information about an object without physically being in touch with the object

• Map is a flat representation of Earth’s curved surface

• Area may be distorted in size, shape, distance or direction

• Map of a city shows slight distortion

• Map of earth shows greatest distortion

• Map projection

• A flat map that represents a spherical surface

• Meridians appear as straight, parallel lines that have an equal amount of space between them

• Parallels and meridians form a grid (locating positions is easier)

• Place a sheet of paper against a transparent, lighted globe so that paper touches the globe at only one point

• Great for air travel and finding great circles

• Little distortion at point of contact

• Unequal spacing between parallels causes distortion in both direction and distance

• Made by placing a paper cone over a lighted globe so that the axis of the cone aligns with the axis of a globe.

• Touches the globe at a parallel

• Where the cone and globe are in contact have the slightest distortion

• North on top, east on the right, south on the bottom, west on the left

• Never Eat Soggy Waffles

• Parallels run from side to side

• Meridians run from top to bottom

• Legend- a list of map symbols and their meanings

• Scale- the relationship between the distance shown on a map and the actual distance

• Graphic Scale- Printed line that has markings on it that are similar to those on a ruler

• Fractional Scale- 1:25,000 (one unit of distance represents 25,000 of the same unit on earth

• Verbal Scale- Sentence form (One cm is equal to one km)

• A line on a map that represents a constant or equal value of a given quantity

• Meteorologists use to show atmospheric pressure

Types of Maps

• The size and shape of the land surface features of a region including its relief

• Natural features

• Shows elevation

• The height of an object above sea level

• More detailed information about the surface

• Shows size, shape and elevation

• Contour lines- a line that connects points of equal elevation on a map (is an isogram)

• Relief- the difference between the highest and lowest elevations in a given area

• Widely spaced contour lines indicate gradual change in elevation

• Closely spaced contour lines is a rapid change in elevation

• Contour lines that bend to form a V is a valley

• Closed loop contour lines indicate a hilltop

• Major highways-red

• Bodies of water-blue

• Forest-green

• Contour lines- brown and black

• Show distribution of geologic features

• Types of rocks, locations of faults, folds, etc.

• Geologic unit- volume of rock of a given age range and rock type

• Assigned by color

• Letters represent age

• One capital letter- symbolizes age of rock

• Lowercase letters- represent the name of the unit or type of rock

• Contact lines-indicates places at which two geologic meet

• Strikes-indicates direction in which beds run

• Dips- Indicates the angle at which the beds tilt

• Two types of contacts

• Faults- cracks where rocks can move past each other

• Depositional contacts-show where one rock layer formed above another

• Classify, map and describe soils

• Based on soil surveys

• NRCS (Natural Resources Conservation Service maps soil

• Soil Survey

• Text- general information about the geology, topography and climate of area being mapped

• Tables- describes and volumes of soils in the area

• Maps-

• General map shows the approximate location of different types of soil within the area