Maps

Mr. Martin

Models• Model of Car

– Advantages– Disadvantages

• Name a Model of the Earth– Globe

• Advantages• Disadvantages

– Maps• Advantages• Disadvantages

Direction• Axis• Geometric north• Cardinal Directions

– North, South, East and West– Compass Rose

• Magnetic North– Compass– 360 degrees– Magnetism of Earth– Declination

• NOAA Declination tool - http://www.ngdc.noaa.gov/geomagmodels/Declination.jsp

Latitude

• Latitude – – Northern Hemisphere - 0 (equator) to 90 degrees

north (north pole)– Southern Hemisphere - 0 (equator) to 90 degrees

south (south pole)– Measuring angle to sun at highest point with

adjustment for time of year (NEVER LOOK AT SUN) – see http://www.pbs.org/weta/roughscience/series1/challenges/latlong/

– At night angle of north star

Longitude

• Measures degrees east or west of the Prime Meridian – 0 degrees

• The Prime Meridian runs through Greenwich, a district in London, England

• 0 to 180 degrees east of Greenwich

• 0 to 180 degrees west of Greenwich

Longitude and Time

• Every 15 degrees represents one hour difference in time from Greenwich– 360 degrees/24 hours = 15 degrees per hour

• If you know the time in Greenwich and you know the local time, you can calculate your longitude

• Local noon can be found when the sun is in its highest point in the sky

• Greenwich time can be found with an accurate clock set to Greenwich time

Longitude and Time Continued

• While accurate clocks are taken for granted today, accurate clocks were not available in the early 18th Century especially on the high seas

• English clockmaker John Harrison in the later half of the 18th Century devised a reliable and accurate clock– He won a prize from the British Parliament– His invention saved thousands of sailors’ lives

Designating any Location on Earth with Latitude and Longitude

• Latitude and longitude is like the coordinate plane we use in math

• We can designate any location on Earth by stating its latitude and longitude

• Looking at the globe, what is the latitude and longitude of Solana Beach?– Latitude – about 32° North Latitude– Longitude – about 118° West Longitude

Designating Latitude and Longitude Continued

• With a larger map, we could estimate the latitude and longitude more accurately

• With Satellite Data, we can get the latitude and longitude of the front door of Keystone Academy– 32°59’22.16”N latitude, 117°15’34.27”W longitude

Google Earth

Latitude and Longitude dataLatitude and Longitude data

• Allows an aerial view of anywhere on Earth

• Based on satellite images

You are here!

GPS – Global Positioning System• Developed from military satellite information• Became available to the public in the late 1980s

and early 1990s• Based on data from 24 satellites• Receiver can pinpoint your latitude and

longitude within a few meters• Most receivers now also are loaded with base

maps showing your position on a map with directions to a designated position

• Has revolutionized vehicle, marine and wild lands navigation in the last two decades

GIS - Geographic information system

• “A GIS is a computer system capable of capturing, storing, analyzing, and displaying geographically referenced information; that is, data identified according to location.” – http://egsc.usgs.gov/isb/pubs/gis_poster/

• GIS in recent years has greatly enhanced natural resource planning and management

• Can have multiple layers showing e.g. elevation, satellite images and resource information

Remote Sensing and Landsat

• http://landsat.gsfc.nasa.gov/

Problem – How to show a sphere on a flat piece of paper!

• Mercator Projection

• Conic Projection

• Azimuthal Projection

Information Shown on Maps (pages 44-45)

• Title• Maps scale• Graphic scale• Verbal scale• Representative function• North arrow• Legend• Date

Topographic Maps

• Topographic maps show elevation by lines of equal elevation

• Topography is the detailed description of the surface features of a region

• Contour lines show lines of equal elevation– Model

• Contour interval is the difference in elevation between one contour line and the next

Model of Topographic map

• http://www.ehow.com/print/how_5824744_make-topographic-mountain-map-school.html

USGS Topo Maps

• The United States Geographical Survey, a federal government agency, makes detailed topographic maps

• USGS Topo maps are generally 7.5 minute maps – They are 7.5 minutes of latitude by 7.5 minutes of longitude. The areas vary between 49 to 64 square miles depending on latitude. http://egsc.usgs.gov/isb/pubs/booklets/usgsmaps/usgsmaps.html

More on Topo Maps

• Contour intervals on USGS maps is 20 feet with darker lines every 5 lines or 100 feet

• Close lines on topo maps mean the terrain is steeper

• Widely spaced lines mean the terrain is flatter• Concentric circles mean a (conical) mountain top• Concentric circles with hash marks mean a

depression like a crater• V shape means valleys. The point of the “v”

points uphill

USGS Maps on Internet

• In addition to paper maps you can buy, USGS provides all its topo maps online for free!

• http://nationalmap.gov/

• Quickstart guide - http://nationalmap.gov/ustopo/quickstart.pdf

• Store - http://store.usgs.gov/b2c_usgs/b2c/start/(xcm=r3standardpitrex_prd)/.do