Download 1_ The Earth - St. Raymond High School for Boys

The Earth
Parts of the Earth
I.
Lithosphere: outer surface of solid rock
A. Two parts to the lithosphere
1. Crust: the outer most surface
2. Rigid Mantle: below the crust
a) Extends to the Moho: the Moho separates both the oceanic crust and continental crust from underlying mantle
(ESRT p.10) boundary on which the plates move
B. Two Types of Lithospheric Plates
1. Oceanic Crust:
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Thinner
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More dense
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Composed of more mafic materials (SiMa)
2. Continental Crust:
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Thicker
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< dense
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Composed of more felsic materials (SiAl)
II: Hydrosphere – layer of Water
A. Three locations:
1. Ground H2O
a) Water that infiltrates the earth
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Aquifer- underground lake
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Spring: ground H2O reaches the earth’s surface
2.
a)
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Surface H2O
All H2O that rest on the surface
Lakes
Oceans
Rivers
Glacier
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3. Atmospheric H2O
H2O vapor in the atmosphere
III. Atmosphere
A. Composition
1. 78% Nitrogen
2. 21% Oxygen
3. .04% other (trace gasses)
B. Four Main Layers or Temperate Zones (ESRT p.14)
1. Troposphere
a) Contains most of the earth’s H2O vapor, resulting in weather
b) Tropopause: the boundary between this & the next layer…
2. Stratosphere
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Reaches 50km above the earth
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The layer where commercial planes fly
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Contains the ozone
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Stratopause: the boundary for the Mesosphere
3. Mesosphere:
a) extends up to 85kmm above the earth’s surface
b) Coldest layer
c) Mesopause is the boundary
4. Thermosphere: outermost layer
a) Hottest layer - 2000oC +
5. Ionosphere:
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layer of charged particles (ions) which protects us from solar flares.
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Responsible for creating the Aurora Borealis aka the Northern Lights
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Northern lights
Shape of the Earth: Oblate Sphere 25,000 mi in circumference
Early Observations
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Ships sailing away
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Shadow of the earth’s moon
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Altitude of Polaris (the North star)-
- the altitude will increase as you move N
- when an observer is @ the N pole, Polaris is directly overhead, which is called your ZENITH
*** the altitude of Polaris = the latitude of the observer
Astrolabe: instrument to measure the angle of a star
Modern Observations
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The weight of an object is slightly < @ the equator than @ the poles
- weight is a result of gravity
- gravity is affected by mass & distance
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Pictures of earth from space
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What would make a good model of the earth?
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Mapping Our World
Intro:
The science of making maps is called cartography. One uses imaginary grid of parallel (//) lines to locate points on the
earth exactly. The equator (eq), is an imaginary line the circles the earth ½ -way between the north (N) & south (S) poles; it
separates the earth into = halves called the Northern & Southern hemispheres (hemi=1/2)
Latitude & Longitude
I.
Latitude: (lat): lines running // to the equator are called lines of latitude.
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Lat. Is the distance in degrees N or S of the eq.
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The equator serves a reference point & is numbered 0o lat.
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The poles are numbered 90o lat
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Lat is measured from 0o @ the eq. to 90o @ the poles
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Locations N of the eq. referred to by degrees N lat (N)
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Those S of the eq. by degrees S lat (S)
A. Degrees of Latitude: Earth is a sphere & can be divided into 360o .To locate positions more exactly, the 360o have
been broken into 60 smaller unites called minutes, whose symbol is ’.A minute can be further divided into seconds
symbolized by ”. Longitude is also measured in degrees, minutes, & seconds
Determining parallels of latitude. Diagram on the left shows the // @ 15oN, 45oN, & 30oS, which is circle. All
points of which are at the same angular distance (15oN, 45oN, & 30oS) from the equator. The diagram on the right
shows parallels of latitude on a map.
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Key areas of Latitude
Tropic of Cancer: 23.5oN
Tropic of Capricorn: 23.5o S
Arctic Circle: 66.5oN
Antarctic Circle: 66.5oS
In between the tropics & the circles are the areas that have the 4 seasons
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II. Longitude (long.): Positions in east (E) & west (W) directions aka as meridians . Long. is the directions, E & W of
the prime meridian (PM), the reference point of long. The prime meridian represents 0o long.The PM is located in
Greenwich, England.
Points W of the pm are numbered 0o to 180o west long. (W)
Those E of the pm are numbered 0o to 180o east long. (E)
Determining meridians of longitude: a) the cut out section on the left represents an angular distance of 80o
measured west from the prime meridian (0o longitude). Also seen is location of 50o N latitude, which leads us to a
location of 50oN latitude, 80o W longitude. The diagram on the right shows meridians of longitude on the map.
A. Semicircles: lines of long., unlike those of lat, are NOT //; they’re large semicircles that extend vertically from polepole.
B. Degrees of long: are fairly consistent distances. Lines of long. Converge @ poles into a point.
C. Locating Place w/Coordinates: both lat & long are needed to precisely locate a position on earth. When measuring,
the lat comes 1st in referencing the coordinates.
• Eg: the precise location of New Orleans, LA is: 29o 57’N, 90o04’W
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To Sum:
Lat= N & S of the equator
Long = E & W of the prime meridian
1. Navigation: Is the science of locating your position. Each place on earth has its own unique coordinates of Lat &
long .Any location N of the equator has a lat = to the angle of Polaris (the N star’s altitude) above the horizon.
Eg: NYC lat is 40oN, the angle of Polaris above the horizon.
To find Polaris in the night sky, look for the big dipper. If the sky’s clear, the big dipper is always seen in the
northern part of the sky ( although it may be tipped on its side or upside down) .The 2 stars @ the end of the
bowl are known as pointer star b/c a line connecting these 2 stars ALWAYS point to Polaris, regardless of where
the big dipper is in the sky
*** The altitude of Polaris = the latitude of the observer
In what constellation is the Big & Little Dipper found?
Why Doesn't Polaris Move? Polaris is very distant from Earth, and located in a position very near Earth's north celestial
pole. Earth rotates once a day on its axis, an imaginary line that passes through Earth from its north pole to its south pole. If
that imaginary line — the axis — is projected into space above the north pole, it points to Earth's north celestial pole. As the
Earth spins on its axis, it also “spins around” the north celestial pole. Polaris, located almost exactly at the north celestial
pole, the center of spin, stays in the same place, while stars farther away from the north celestial pole can be seen to move
in a wider circle around Polaris as viewed from Earth during its daily rotation. Polaris actually lies just a short distance away
from where Earth's axis points. Polaris is located about 1 degree off to the side of the north celestial pole, so Polaris does
move a little, tracing a very small arc in the night sky, around which the other visible stars make wider circles.
**** At the North Pole, the North Star appears directly overhead. At the Equator, the North Star is seen on the horizon;
south of the Equator it cannot be seen at all. At any point in the Northern Hemisphere, the height of the North Star above
the horizon, measured in degrees, is very nearly equal to the latitude of the observer. The North Star, therefore, serves as a
method of determining position as well as direction.
2. Finding the altitude of a star w/an astrolabe: The altitude of an heavenly body is its angular height above the horizon of
an observer. One can measure the altitude using an astrolabe: a protractor w/heavy weight suspended. When one sights a
star along the edge of the astrolabe, the wt hangs straight down towards the earth’s center of mass. A line @ a right angle
to the line formed by the string from which the wt is suspended represents the plane of the horizon.
III. Time Zones: The earth takes ____ hrs to rotate once on its axis; therefore, there are ____ time zones, each representing
a different hour of the day. Each time zone is 15o wide, roughly corresponding to the lines of long. Time zone boundaries
have been adjusted for convenience: Eg: if a city was split by different time zones w/in it there’d be great confusion (are
there any? Look it up). So the time zone boundary is moved outside the city . However, large countries like the U.S. have
several time zones; eastern, central, rocky mountain (mountain time) western, Pacific, Alaska standard, & Hawaii standard
time. If it’s 9am in da Bronx, it’s 8am in MN, 7am in MT & 6am in CA. What’s the time in Hawaii?
B. Calendar dates: Each day ends/begins @ 12 midnight: 12am. Every time zone experiences this, w/the calendar date
advancing to the next day. Each time you travel thru a different time zone you’ll gain or lose time until, @ some point, you’ll
gain or lose an entire day
1. International Date line: or 180o meridian, serves as the transition line for calendar days. If you were traveling W across
the date line, you’d advance 1 calendar day; if flying E, you’d move back 1 day.
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Fields
I. Intro
A field is a region of space in which similar quantity can be measured @ every point or location.
A. Isolines: connect points of = value on a field map
B. Isotherms: connect pts of = To
C. Isobars: connect pts of = pressure
D. Contour lines: connect pts of elevation
Elevation is being measured in this topographic field. Many points in a region have been measured & plotted on a map,
& isolines (contour lines) are drawn in connecting points of equal value in a region
II.
Topographic Maps: A topographic or contour map shows the shape of the earth’s surface; heights may be shown as
numbers on such a map. W/this kind of map you can see features such as: lakes, rivers, mountains, plains, & hills.
A. Contour lines: (isolines) drawn on the map give elevations: heights above or below sea level (lvl) (see below)
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Each contour line is separated from the next by a uniform distance in a elevation known as the contour interval
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The interval is the difference between 2 adjacent lines
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Where lines are close, the slope of the ground is STEEP
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Where lines are far apart, the slope is GENTLE
1. Sea Level: Some areas on earth are taller than others. To measure elevations we always start @ the same place – the
level of the sea where it meets the shore. Hence the term “sea-level”.
B. From the shape of contours you can recognize landscape features such as hills, valleys, depressions, etc. (see h.o.) A
contour map may also use symbols or color to represent bodies of H2O, vegetation, & structures. A key or legend describing
the symbols & meaning is usually provided. Remember! That thru time, the landscape will change.
C. Note the following features on H.O.
1. Contour lines connect places w/the same elevation; the darkest lines are the index contours, some of which are labeled
w/their elevations. This one is 50o above sea lvl. What is the contour interval?
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Ans:
2. Contour lines are close around hills & basins or depressions. You can look hachures: short lines @ right angles to the
contour lines that are used to indicate a depression. These lines point to lower elevations.
3. Contour lines NEVER cross – if they did it the spot where they cross would have 2 different elevations.
4. In a stream valley, they’re located in the lowest part of the valleys.
*** Where the contour lines cross streams they make “V’s” which ALWAYS point UPSTREAM. This is b/c streams flow in
depressions that are beneath the elevation of the surrounding surface.
5. The slope or gradient is the steepest where the contour lines are closest.
6. The higher elevations on the map are found where the contour lines make small closed curves.
D. Map Scale: explains what the measurement on a map are = to: eg below: 1”= 2000’
E. Map Legend: explains what the symbols on a map mean
Isolines
I.
Field Maps: regions of space that has a measurable quantity.
A. Isolines: lines that connect points (pts) of = value.
1. Rules for drawing isolines:
a) draw in smooth curved lines
b) they tend to be //
c) Draw @ regular intervals- the change between each line has to be the same thru the entire map
d) They NEVER cross
e) They connect pts of the exact same value
f)
They just can’t end: they go to the end of the paper or they form a closed circle
II.
Contour Maps
• Also called Topographic Maps – maps that show the shape of the land
A. Contour lines: isolines that connect pts of = elevation
1. Contour interval: the change in elevation between 1 contour line & the next
2. Index contour: contour line in bold print that has elevation labeled
3. Depression Contour: contour line w/hachure marks indicating a low spot or depression
B.
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1.
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3.
Distance
Refers to the scale of the map
Ratio: 1:1000 means that 1 of any unit on the map is = 1000 of those units on the earth’s surface
Verbal Scale: 1cm = 1 km
Graphic scale: is a ruler printed on the map and is used to convert distances on the map to actual ground distances.
C. Gradient: pg.1 ESRT
1. Change in field value distance
2. Change in field value is determined by reading the isolines
3. Distance is determined by using the scale on the map. On the maps the gradient is greatest where the lines are
closer together
4. The gradient on a topographic map is the steepness of the hill: the closer the lines, the steeper the hill. The
wider, the more gentle the grade or slope or gradient.
D. Profile: the side view of a topographic map
Steps in drawing a topographic profile:
1. First, 2 pts must be chosen thru which the profile will be drawn & a straight line should be drawn
2. Next place a piece of paper over the line & make a mark @ each pt that your line intersects the contour line & also
label the elevation for each mark.
3.
Then you need to create an x & y axis that matches your map.
4. Draw an x& y axis
5. Use your paper w/the marks as your x axis
6. Label the y axis using the same interval as the map & including all the elevations from the x axis
7. 4. Plot the pts by going up from the points marked by the x axis to the labeled elevation
8. 5. Lastly, connect all pts in order, w/a smooth, curved line
9. *** careful when you have 2 dots w/the same elevation: you have to draw the line higher or lower. This happens @
the top & bottom of a hill
End for Exam