Chapter 6 Views of Earth Sections 2 & 3: Latitude and Longitude and Maps

Latitude The equator is an imaginary line that circles the Earth halfway between the north and south poles. It separates the Earth into two equal halves – the northern hemisphere and the southern hemisphere. Latitude is the distance, measured in degrees, north or south of the equator. These lines are horizontal, parallel, and never intersect. The equator is 0 degrees latitude and the poles are 90 degrees latitude. Locations north and south of the equator are referred to by degrees north latitude or degrees south latitude. The degrees are further broken down into minutes and seconds.

Latitude

Longitude The prime meridian is an imaginary line that runs vertically from the North Pole through Greenwich, England, to the South Pole. This line separates east from west. Longitude is the distance east or west of the prime meridian. These lines are vertical and never intersect, but the lines do meet at the poles. Longitude is measured from 0 degrees to 180 degrees. The prime meridian is 0 degrees longitude. Points east or west of the prime meridian are referred to by degrees east longitude or degrees west longitude. Unlike the equator, the prime meridian does not circle the Earth. The line of longitude on the opposite side of Earth from the prime meridian is 180 degrees longitude, call the International Date Line.

Longitude

Finding Locations Latitude is written first in a coordinate set. Latitude is given north or south of the equator. Longitude is given east or west of the prime meridian. Examples: 30degrees N, 90degrees W = New Orleans, Louisiana

Coordinate Set

Time Zones Time is measured by tracking Earth’s movement in relation to the Sun. Each day has 24 hours, so Earth is divided into 24 time zones. Each time zone is 15 degrees of longitude wide and is 1 hour different from the zones beside it. The United States has 6 different time zones. As you travel from east to west across the U.S., you lose an hour. Ex. 5 pm Eastern Time is 4 pm Central Time is 3 pm Mountain Time is 2 pm Pacific Time. When you travel across the International Date Line, you gain or lose a whole day. If you travel west across the International Date Line, you move forward one day. If you travel east across the Line, you move back one calendar day. Ex: If you flew from Hawaii on a Friday, it would be Saturday when you landed in Australia.

Time Zones of the United States

International Date Line

On the handout find the continent using the following coordinates 60o N, 140o W : 20oN, 20oW : 20oS, 60oW : 40oS, 140oW : 50oN, 20oW : 80oS, 120oE : 20oS, 20oE : 0o, 80oE :

Maps Maps are models of Earth’s surface. The most perfect map is a globe. Maps are made as map projections. A map projection is made when points and lines on a globe’s surface are transferred onto paper. There are three main types of map projections and all of them distort the shape of the landmasses of their areas.

Projections

Mercator Projections Mercator map projections are used mainly on ship. They project the correct shape of the continents, but the areas are distorted. Longitude lines are projected as parallel, making the areas near the poles look much larger than they are.

Robinson Projections A Robinson projection shows accurate continent shapes and more accurate land areas. In this projection, the lines of longitude are curved as they are on a globe, which results in less distortion near the poles.

Conic Projection Conic projections are made by projection points and lines from a globe onto a cone. These are used to make maps of small area, like road maps weather maps.

Topographic Maps A topographic map shows the changes in elevation of Earth’s surface. These maps show natural features and also cultural features, such as roads, cities, and other structures built by people. These maps are helpful when doing outdoor activities like hiking. A contour line is a line on topo a map that connects points of equal elevation. The difference in elevation between two side-by-side contour lines is the contour interval, which stays constant throughout a map. Not all contour lines are marked with the elevation. The ones that are labeled are called the index contours. You can determine the elevation of other lines by adding or subtracting the contour interval from the elevation on the index contour.

Topo Maps

Rules about Contours 1. The closer the contour lines, the steeper the change in elevation. 2. Contour lines close and form a complete circle around the tops of hills or mountains, or the bottom of basins. 3. To tell the difference between a hill or depression, look at the elevation numbers or look for hachures – short lines drawn at right angles to the contour line. These lines point toward lower elevations. 4. Contour lines never cross. If they did, it would mean that the spot where they cross would have two different elevations. 5. Contour lines from Vs that point upstream when they cross streams. *Remember a river flows downstream, or down hill.

Map Scale The map scale is the relationship between the distances on the map and distances on Earth’s surface. Example: A topo map has a scale that reads 1:80,000. This means that one unit on the map represents 80,000 units on land.

Map Legend A map legend explains what the symbols used on the map mean.

Map Series Topo maps are made to cover different amounts of the Earth’s surface. The map series includes maps that measure the same area of the surface. Example: A series may include 7.5 minute maps. These cover 7.5 minutes of latitude by 7.5 minutes of longitude of Earth’s surface.