GIS on the Web
Google Earth shows high resolution satellite imagery of our planet, map overlays and user-added points of interest (you can even add stuff!). It is an amazing tool for many different disciplines.
Latitude and longitude, divide the earth into a grid-like coordinate system.
Latitude lines are parallel to the earth's equator. Latitude lines run from 90ºN at the north pole to 0º (the equator) to 90ºS at the south pole. Lines of latitude are noted as being either NORTH, or SOUTH, meaning north or south of the equator. So, for example, the Longitude lines are equidistant lines (they are all the same length) that run from the north pole to the south pole.
Longitude lines run from 180ºE to 0º (at the prime meridian which runs through Greenwich, England) to 180ºW. Lines of longitude are expressed as being either EAST or WEST, meaning east or west of the prime meridian. The international date line is located where 180ºW meets 180ºE.
- 'Grab' the earth (click with your mouse) and move the earth right and left (east and west). Notice how the lables for the lines of latitude (they should say something like "N50, N30, N10") stay in the same place as you move east and west.
- Next, grab the earth and move up and down (north and south). Notice how the labels for the lines of longitude stay in the same place as you move north and south.
How we divide latitude and longitude
Latitude and longitude lines are expressed in degrees ( º ), minutes ( ' ) and seconds ( " ) with a directional notation (N, S, E or W). Minutes and seconds run from 0 to 60 (e.g. 60 seconds equals one minute, 60 minutes equals one degree). For example, something that was 120 degrees, 10 minutes and 30 seconds west longitude would be denoted 120º10'30"W. The 'squares' defined by latitude and longitude are really not squares at all because they are on the spherical earth (though they look like squares on a flat map!).
- Zoom in on the earth. Notice as you zoom in how degrees, minutes and seconds begin to show up.
- Look at the bottom of the screen. Notice the latitude and longitude location for your mouse is written in degrees, minutes and seconds along the bottom of the screen.
Try this: Use Google Earth to navigate to the following locations.
For example you can type in (or copy and paste) a latitude and longitude (such as 48 4'0N and 42 20'E), or the name of a major geographic feature (Grand Canyon) and Google Earth will 'fly' you there. You can see the country that you are located in by turning on the borders layer. You can also use your atlas for reference.
You can copy and paste the latitude/longitude locations below into the Google Earth 'fly to' window.
1. Go to 19 28'08.35"N, 155 35'25.06"W What do you see at this location? What country is it in?
2. What city & country is located at 33 51'24.28"S, 151 12'55.37"E?
3. Go to 48 51'29.83"N, 2 17' 40.11E. What do you see at this location? What city and country is this in?
4. Go to 3 04' 32.59"S 37 21' 14.57"E. What do you see at this location? What country is this in? (hint: turn on the places of interest -> Geographic Features layer).
5. Go to 37 47' 42.39"N 122 24' 09.52"W. What do you see at this location? What country is this in? (hint: turn on the 3-D buildings layer).
- In Google Earth, go to Foothill College (12345 El Monte Road, Los Altos Hills, CA) -- or the address for your school.
- Open the measure tool (along the top, it looks like a ruler).
- Measure the length of the Foothill campus from east to west using the measure line tool.
6. What is the east/west distance of the Foothill campus in kilometers?
- Zoom in on the track around the football stadium. Use the measure path tool to measure the distance around the track.
7. What is the distance around the track in miles?
- Browse the pre-loaded layers. Note that you can turn them on and off using the check boxes. Go to 'State of the Ocean' and select 'Sea Surface Temperatures'. You will have to zoom to the Navy Research labs and click on the icon to download the overlay. The overlay will appear in your Places' sidebar under 'Temporary Places'. Turn on the Most Recent and the Animation. You may need to step through the animation to force it to load properly (depending on your internet speed). Zoom out until you can see the whole earth. View the animation.
8. Compare the ocean surface temperature off of the west coast of the USA with the temperature off the east coast. Which is warmer?
Another innovative way to display geospatial information is as an animation over time. View the changing world infant mortality rates in Google Earth.
9. After you view the animation, describe (about 1 paragraph) how the infant mortality rates have changed over time in Africa, Asia and Europe. Cite specific examples.
Web GIS allow you to interactively view and query maps. The city of San Jose crime map is a good example. Visit San Jose crime maps and focus on the area around San Jose State University (near the intersection of highway 280 and highway 87. View the past 7 days (default value) Answer the following questions:
10. What is the difference between the label 'T' and 'TV'?
11.Use the calendar to view only the time period that your teacher tells you to. Use the pull down menus at the bottom of the screen to view a list of the Robberies in that time period. How many robberies were there in this time period?