Topic 2 Earth’s Dimensions

Earth’s shape Oblate sphere Slight bulge in the middle Due to the rotation of the earth

Evidence of earth’s shape Ships disappear past the horizon Earth’s shadow on the moon during a lunar eclipse Time difference between distant places Altitude of stars change (polaris) cannot be seen in the southern hemisphere Photographs from space

Spheres of Earth Lithosphere: solid part of Earth – Includes crust, upper mantle, bedrock, continents, ocean floor

Spheres of Earth Hydrosphere: water on Earth – Includes ocean, lakes, rivers, groundwater – Approximately 75% of Earth’s surface

Spheres of Earth Atmosphere: shell of gases that surround Earth – Divided into layers based on composition and temperature Troposphere- layer closest to the surface – Most important layer – All weather events happen here

Locating Positions on Earth Coordinate system: a grid where each location is defined by the intersection of two lines What do we use on Earth?

Latitude Line of 0 = equator Lines are called: parallels Lines run: east to west Lines measure: north and south of equator Highest degree: 90 degrees

Latitude Altitude of Polaris= a persons latitude

Longitude Where is 0 degrees: prime meridian Lines are called: Meridians Lines run: north and south, intersect at the poles Lines measure: east and west Highest degree: 180 degrees

Longitude Locations with the same longitude have the same solar time Earth’s rotates at 15 degrees per hour Time zones are 15 degrees apart

What happens if we round to the nearest degree? 42.4 ° and ° 42°15’00’’ 42°15’15’’

Landscape Regions Mountains: high relief landscape, has distorted rock structures

Landscape Regions Plateau: High relief, not as high as mountains, has horizontal bedrock

Landscape regions Plains: low relief, gentle slopes

Landscape regions Valley: a dip or low lying area between two mountains or plateaus

Mapping Fields Field: a generic term for anything being measured Isolines: line that connects points of equal value Isotherms: lines that connect equal temperature Isobars: lines connecting equal barometric pressure

Mapping Fields Maps: a snapshot of a particular area – Fields do not end at the edge of the map – Contour lines: lines that connect equal elevation – Contour interval: difference in elevation between two adjoining contour lines

Drawing isolines Try to locate a pattern where numbers may be bunched together Draw the missing lines in the diagram in your notes.

Topographic Maps Map Scale: Measures distance across the surface Contour interval: difference between two adjacent contour lines (20 meters)

Topographic Maps Direction of stream flow: – Always flows downhill (from high elevation to low elevation) – Contour lines bend uphill

Topographic Maps Steepest section: where the contour lines are closest together Bench mark: states the exact elevation at a particular location

Topographic Maps Depressions – The first depression contour has the same value as the previous contour line – Any other depression contour counts down with the same contour interval

Topographic maps Islands – The first contour line is zero if and only if the island is surrounded by the ocean

Topographic Maps Highest elevation: – Is one less than the next highest contour line

From RegentsEarth.com

This topographic map shows a region of space (a field) as it would appear if you were directly above it. Your job is to convert this ‘above’ view into a side- ways view, a profile of the region from point A to point B. You will need a pencil and a ruler (or other straight edge). First: draw a line from point A to point B. At every point where line A-B crosses a contour line you will have to draw a line straight down to the corresponding line on the grid below.

Since you’re just starting out it may be helpful to make a small mark at each point where you will draw a line. This may prevent you from missing points. By counting these marks, there are 16 of them, you will know that you must draw 16 lines. Later you can check yourself to be sure you have drawn them all. The first mark you made was at point A. Notice that point A is on the 200m contour line. You must now draw a vertical line from point A to the 200m line on the grid below. The next mark is on the 300m contour line. Draw a vertical line from that mark to the 300m line on the grid below.

Now continue to draw straight, vertical lines from each mark to the appropriate line on the grid below. Using a pencil, connect the bottoms of the lines. Try to connect them with one smooth, curving line rather than a series of short, straight ones. Please notice that here the line went above 500m but well below 600m. That’s because this area of the map is above 500m but less than 600m. We know this because there is no 600m contour line here.

The same principle applies here. Your line must go below the 300m line and above the 200m line. That’s because if you were standing here you would be between the 200m and the 300m contour lines. And again, if you were here your altitude would be more than 600m but less than 800m (there is no 800m contour line on this map). Therefore you must be careful to make your line here go above 600m and below 800m. Make it OBVIOUS! Make your lines go in the middle between the grid lines so anyone scoring your profile will understand.

OK. Final check. You were supposed to draw 16 lines. Did you? Are the lines you drew straight, parallel and vertical? Are all the lines drawn to the proper grid line? Do your peaks and valleys go obviously between grid lines? Why bother checking? Because most students lose points not because they don’t know how to do this but because they’re SLOPPY! Good enough ISN’T good enough!

A slightly different situation: Here we have another contour map. Your job is to construct a profile along a straight line from points A to B. The problem is that the grid on which the profile is to be constructed is in the answer booklet on a completely different page. To make matters worse, the line A-B on this map is on a slant. What to do?

STEP ONE Using the contour interval below the map, carefully label each contour line crossed by line A-B with its elevation Make sure you don’t label this line It’s not a contour line. It’s Colden Creek. So we can check ourselves later, count how many lines are labeled starting with the 550 line at point B. You should have counted 10 lines. When we’re finished we can check to be sure we’ve drawn them all.

STEP TWO Place a blank piece of paper (here shaded blue) over the map just under line A-B. Make a small mark on the paper by each contour line. Now label each mark with the value of the contour line it represents. 550 and label A and B so you’ll know which end is which. A B Reminder: The number 533 is the maximum elevation of Aurora Hill and the triangle marks that spot. It is NOT a contour line and should be ignored.

STEP THREE This is the grid as it appears in the answer booklet provided with the regents. You are to construct your profile on this grid. Take the paper you marked with the contour line values and line it up below the grid so that the ‘A’ mark on the paper is below ‘A’ on the grid and the ‘B’ mark on the paper is below ‘B’ on the grid. Now, just as you did in the first example, take a straight edge and carefully make an X on the grid correspond- ing to each value on the paper below. The X for points A and B have been made for you.

STEP THREE x Many students prefer to draw the lines but you do not have to. You can just put in the X’s x x xx x x x Now connect the X’s using a single, smooth, curving line. Be sure your ‘peaks’ and ‘valleys’ go above and below grid lines just as in the first example. One last check. You were supposed to have marked 10 points on this grid. Are they all there? YES! Counting the points marked for you (A and B) there are 10 X’s. WELL DONE

1.Label the contour lines on the map, above the profile 2.Place a scrap paper across the profile line and mark each place a contour line touches the paper. Mark the elevation 3.Place the scrap paper at the bottom of the graph. 4.Place a dot directly above each mark on the scrap paper at the corresponding elevation 5.Connect the dots with a smooth line Hills are not flat- the line at the top of the hill must be a little above the highest elevation on the graph. Valleys are not flat- the line at the bottom of the valley must be a little below the lowest elevation on the graph Steps to make a profile:

Gradient Where is the formula? – What is it?

Gradient Example A stream begins at an elevation of 250m and flows into a pond that is at an elevation of 100m. The length of the stream is 10km. What is the gradient?