Maps! Learning how to read them and what information they can tell you!

What is cartography? - The study and practice of making maps

What is a map? A flat representation of the Earth or part of Earth’s surface Why use or make one? --locate specific places --determine routes from one place to the other --define borders

Types of Maps There are many different types of maps, but all show some sort of distortion (i.e. shapes or sizes of landmasses are not accurate) The most commonly used map that you have probably seen is the Mercator Projection.

Mercator Projection Has parallel lines of latitude AND longitude As a result, landforms near the poles (Greenland, Antarctica) are greatly exaggerated in size

Why are the lines at the poles exaggerated?

So where in the world are we? 38°38’55.68” N 72°23’03.70” W 3, &z=16&t=h&hl=en 3, &z=16&t=h&hl=en

What is latitude? Lines running parallel to Earth’s equator Used to measure north and south of the Equator

Latitude Cont’d Lines of latitude are parallel and do not intersect They are sometimes referred to as PARALLELS! Each degree = 111km Equator=0 o Poles =90 o N/S

What is Longitude? Measurement of Earth east and west of the prime meridian Lines of longitude are sometimes referred to as meridians!

Longitude Cont’d Meridians converge at the poles They run from one pole to the other going north and south Prime Meridian = 0o International Date Line = 180o

The Prime Meridian

At what point on Earth are both latitude and longitude 0 degrees? Where the prime meridian crosses the equator!

More on Latitude and Longitude All points in the United States are north latitude and west longitude! When you write the coordinates for latitude and longitude, you ALWAYS write the latitude first, then the longitude! –EX: (15N, 30E), (0, 47W), (33S, 5E)

Time Zones To keep world wide time consistent, the Earth is divided into 24 time zones Each time zone = 15 o longitude

Time Zones Why? 360 degrees / 24 hours = 15 o /hour GMT = Greenwich Mean Time (also called UTC= Coordinated Universal Time; Zulu Time; World Time) Why? The Prime Meridian crosses through Greenwich, England

The Earth moves through 360 degrees of longitude every twenty- four hours. So how many degrees of longitude does the Earth move in ONE hour? Fifteen degrees

So? If you travel WEST of the P.M. you subtract an hour per time zone If you travel EAST of the P.M. you add an hour per time zone

BUT! There is a line of longitude that is called the International Date Line (IDL). When you cross this you change days! If you cross the IDL traveling WEST you ADD a day (you’d be in tomorrow) If you cross the IDL traveling EAST you subtract a day (you’d be in yesterday)

Aerial Photographs

AERIAL PHOTOTOPOGRAPHIC MAP

Topographic maps

Topographic Maps Show changes in earth’s elevation, and locations Contour lines — connects points of equal elevation Contour intervals — the difference between two adjacent contour lines Depression lines — shows areas lower than surrounding landscape

Topographic Maps Cont’d The closer the contour lines are, the steeper the slope! That means that the farther apart the contour lines are, the more gentle the slope is!

Topographic Maps Cont’d Sea level is always 0, this can be very helpful when trying to find the contour interval! If you see contour lines in the shape of a “V” that means there is a river there! The contour lines always point in the direction the river is flowing from!

Topographic Profile By using a topographic map, you can draw what the area would look like from the side (instead of looking down on it!). We will practice this together and will make more sense then. You need to be able to recognize which topographic profile fits which topographic map, so make sure you practice!

Map scales A ratio between measured distances on a map and actual distances on Earth. [ Ex: 1:10000] So? 1 unit on a map equals units on Earth’s surface [units can be cm, km, mi, ft, etc.]

More on Map Scales There are three different types of map scales – Graphic – Verbal – Fractional (Ratio)

More on Map Scales The larger a map scale is, the more detail it shows! – 1:20,000 is LARGER than 1:63,000 (the actual fraction/ratio is larger!) – That means that the map scale with the MOST detail is 1:20,000!

Introduction to GPS Many features have addresses and landmarks to get you to a destination. However, there are many features that do not have addresses… And then there is the open ocean and sky…

Pre-GPS Navigation is critical!!! Historical Navigational tools have limits. This is why people wanted to develop a more accurate tool to help navigate.

The military had its own reasons for determining location… - Identify targets - Friendly fire issues GPS was developed by the Department of Defense Funding for the GPS was contingent on making the system available to the public!

What is GPS? GPS is not a single UNIT! There are three major components in this system: 1.Satellites 2.Ground Control Stations 3.GPS Receivers (or units) GPS = Global Positioning SYSTEM

GPS The satellites continuously send radio signals towards earth. The radio signals contain several pieces of information, including the satellite id#, a time stamp, and the satellite’s true position in space. Control stations continuously track satellites, and update the positions of each satellite. GPS units are referred to as “receivers”. GPS units are referred to as “receivers”. They receive information (radio signals) from satellites.

How GPS Works Signal with Time stamp… Satellite ID # Satellite position information

How GPS Works If the GPS receiver only obtains signals from 1 Satellite, then it “knows” that it is located somewhere on this sphere…

How GPS Works If the GPS receiver only obtains signals from 2 satellites, then it “knows” that it is located somewhere where these 2 spheres intersect

How GPS Works If the GPS obtains signals from 3 satellites, then it “knows” that it is located somewhere where these 3 spheres intersect (2 points)

How GPS Works

A fourth GPS is required to determine the exact location and elevation.

GPS has worldwide coverage… HOWEVER… You can lose satellite coverage (or received degraded signals) in areas with dense foliage, in downtown areas, etc. You may also lose satellite coverage (or receive degraded signals) in deep valleys or gorges.

Current Applications of GPS Public Safety Environmental resource agents AviationMilitary Local planning SurveyingRecreationBusiness