Download Regents Earth Science – Unit 3: Measuring Earth

Regents Earth Science – Unit 3: Measuring Earth
Models
Model - a representation of an object or natural event
•
maps
•
globes
•
drawings
•
diagrams
•
graphs
•
formulas
Earth's Shape
Oblate Spheroid - true shape of the Earth
•
slightly flattened at poles, bulging at the equator
•
from space it looks like a perfect sphere
Gravity - pulls inward equally in all directions
•
causes the Earth to be spherical
•
Earth's rotation on its axis causes the Earth to bulge
at the equator
•
•
equatorial diameter = 12,756 km.
polar diameter = 12,714 km.
Evidence of Earth's Shape
1.
2.
Photos from Space - reveal Earth is spherical
Observations of ships on the horizon - appearance and/or disappearance of ships
Evidence of Earth's Shape
3.
Observations of lunar eclipses - show Earth is
spherical
4.
Measurements of gravity - pull of gravity is stronger the
closer you are to the center of earth
–
5.
force pulling down at poles is greater than at the
equator (closer to the center of the Earth)
Observations of the North Star (Polaris) - altitude of Polaris changes as an observer moves
north or south (in Northern Hemisphere)
Latitude and Longitude
Latitude - angular distance north or south of the equator (0°)
•
run east-west
•
measure north-south
Parallels - east-west circles on maps and globes
•
equal distance from each other (parallel)
•
look like lines from equatorial view
latitude - like rungs of a ladder
Latitude and Longitude
Longitude - angular distance east or west of the Prime Meridian (0°)
•
maximum longitude = 180° (International Date Line)
Meridians - north-south semicircles on maps and globes that connect the north and south poles
•
•
any location above the Equator has a latitude of north
any location below the Equator has a latitude of south
•
•
any location to the right of the Prime Meridian has a longitude of east
any location to the left of the Prime Meridian has a longitude of west
Equatorial view:
north
west
east
south
latitude
longitude
Polar view:
Equator (0° latitude)
International Date Line
(180° longitude)
Prime Meridian (0° longitude)
Latitude and Longitude
Reference Tables p.4
Time Zones
Every 15° of longitude equals 1 hour of time
•
when moving east (to the right) time is later
•
when moving west (to the left) time is earlier
77 a.m.
a.m.
66 a.m.
a.m.
•
Earth takes 24 hours to rotate once on its axis
8 am
88 a.m.
a.m.
99 a.m.
a.m.
6 am
4 am
10 am
10
10 a.m.
a.m.
2 am
sunlight
12
midnight
12 noon
10 pm
2 pm
360°
24 hrs.
=
15°
1 hr.
*** Earth rotates 15°/hour
4 pm
8 pm
6 pm
Time Zones
Earth has 24 time zones:
Earth Fields
Field - any region of space that has some measurable value of a given quantity at every point
•
•
•
temperature
air pressure
elevation
Isolines:
isoline - a line that connects points of equal value
1.
2.
3.
isotherm - connects points of equal temperature
isobar - connects points of equal air pressure
contour line - connects points of equal elevation
• never cross
• can run-off map
• never end
Topographic Maps
topographic maps show the elevation of the land by using contour lines
•
man-made features are shown by using symbols
isotherms - temperature
field map of the U.S.
Topographic Maps
elevation - height above sea level
contour interval - difference between 2 adjacent
contour lines
benchmarks - show the exact elevation
index contour line - every 5th line is darkened and labeled
•
helps to read maps
contour interval = 25 m
x
highest possible elevation at x = 174m
depression contour line - special
contour lines that have hachure
marks on the inside
•
used to show a depression (ex.
crater) on Earth's surface
x
depression contour
line elevation =
240m
minimum elevation at x = 221m
contour lines always bend upstream
•
•
lines "point" to higher elevation
streams flow from high to low elevation
(flow opposite the direction the contour
lines point)
stream flow
contours make a "V" that
points upstream
high elevation
Topographic Maps
•
Gradient - the rate at which field values change
from point to point in a field
G=
Reference Tables p.1
G=
∆FV
d
•
the gradient is steepest where the contour lines are closest together
•
the gradient is gentle where the contour lines are far apart
Profile - exaggerated side view of a portion of the earth's
surface along a line between two points
G=
A
B
G=
∆FV
d
200m - 100m
2 km.
50.0 m/km.
Topographic Maps
1.
2.
3.
draw a line between 2 points on a map
place a blank piece of paper along the line you
have drawn
on the blank paper, make a tic mark wherever the
paper crosses a contour line on the map and label
the elevation for each mark
4.
5.
6.
on graph paper, make an appropriate vertical scale for elevation
place the paper with tick marks along the horizontal axis of the graph
and go directly above the tic marks on your paper and make a small dot
on the graph paper at the corresponding elevation
connect the data points
Spheres of the Earth
Atmosphere - shell of gas that surrounds the Earth (least dense)
Hydrosphere - the waters of the Earth (oceans, lakes, rivers, groundwater, ice)
Lithosphere – crust of the earth, dense outer shell composed of rock (most dense)
1.
2.
3.
Reference Tables p. 11
Atmosphere
The Earth's atmosphere has several distinct layers
•
Troposphere – lowest layer, temperature decreases with increasing altitude, has “weather” due to the presence of water vapor
•
Stratosphere – above the troposphere, temperature increases with increasing altitude, contains the ozone layer
•
Mesosphere – above the stratosphere, temperature decreases with increasing altitude
•
Thermosphere – outermost layer, extends into space, temperatures increase with increasing altitude
•
•
the interface between each layer occurs where temperature trend changes
the boundary between each layer is a pause:
•
pressure decreases with increasing altitude
Reference Tables p. 14
Hydrosphere
Almost ¾ (71%) of the Earth’s surface is covered in water
•
very thin layer only 3-4 km. thick (like the skin of an apple)
•
includes oceans rivers, and lakes
Earth’s Interior
Earth’s interior has 5 zones:
1.
Lithosphere – rigid, broken into several plates
2.
Asthenosphere – “plastic like” layer, lithospheric plates are moved by convection currents
within this zone
3.
Mantle – stiffer than asthenosphere, but heat is transferred by convection
4.
Outer Core – liquid, made of nickel and iron
5.
Inner Core – solid, made of nickel and iron
•
•
temperature, density, and pressure increase with depth
outer core is liquid (actual temperature is greater than the melting point)
Reference Tables p. 10