Grade 8 Earth Science
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Transcript of Grade 8 Earth Science
Grade 8 Earth Science
Chapters 14 & 16: Atmosphere & Climate
Composition of Earth’s Atmosphere
Layers of Earth’s Atmosphere
Info. Relating to the Atmosphere
• Troposphere-
• Ionosphere-
Where does weather occur?
Why does the frequency of radio stations break up?
Ozone Layer
• What is ozone?
• What is the ozone layer?
• Where is the ozone layer located?
• How does ultraviolet radiation affect you?
• Describe CFC’s (chlorofluorocarbons)…
Energy From the SunType of Energy Transfer Description Example
Radiation Transfer of energy through electromagnetic waves
Conduction Transfer of energy that occurs when molecules bump into one another
Convection Transfer of heat by the flow of heated material
Water Cycle Words to Know
• What is a cycle? • Evaporation-
Transpiration-
• Condensation-
• Precipitation-
Movement of Air• Winds are caused by the uneven heating
between the Equator & the Poles– Hot air rises– Cool air settles
• Coriolis Effect: deflects all free-moving objects (such as air and water) to the right north of the equator and left to the south
Wind Systems• The Prevailing Winds are caused
by the rotation of the earth and the position of the continents.
SURFACE WINDS• Easterlies –• Westerlies - • Trade Winds – • Doldrums -
HIGH ALTITUDE AND LOCAL WINDS
• Jet Stream – winds at high altitude (where the jets fly). Flows from west to east in northern hemisphere and opposite direction in the southern hemisphere
• Local Winds – are caused by convection currents examples are Sea and Land Breezes
Climate Words to Know:Tropics-
Polar Zones-
Temperate Zones-
What is the difference between
weather & climate?
El Nino ~ La NinaSome climatic changes last longer
than a season…
El Nino is a climatic event that starts in the tropical Pacific Ocean and sets off changes in the atmosphere (unusually warm ocean temperatures)
La Nina is El Nino’s counterpart which causes unusually cold ocean temperatures
Climatic Changes• Greenhouse Gases-
• Global Warming (Climate Change)
Chapter 17: Ocean MotionHow do oceans affect you?How do you affect oceans?
Composition of Oceans
• Earth’s surface is ______% ocean.
• _________ is a measure of the amount of solids dissolved in seawater.
• It has remained nearly ____________ for years.
Elements & Compounds in Ocean Water
Surface Currents• Move water
horizontally • Parallel to earths
surface• Powered by winds
Importance: distribute equatorial heat
to other areas of earth
The Gulf Stream
Upwelling & Density CurrentsUpwelling Density CurrentsCirculation of ocean that brings deep, cold, nutrient-rich water to the surface
TOP to BOTTOM
•Important for fishing!•Contributes to San Francisco’s “famous fogs”
More dense seawater sinks under less dense seawater
HORIZONTAL
Ocean Waves & Tides
• Wave- rhythmic movement that carries energy through ________ or _______
• Ocean Waves carry energy through _________
Breaker- collapsing wave onto the shore
TIDES• Tide =
______ and ______ in sea level
• Tidal Range = the difference between the level of the ocean at ______ _______ and
______ _______
Tides are affected by the gravitational pull of the _______ and _____ on the earth’s waters.
The moon is closer to earth, and therefore, exerts a _________ gravitational pull.
How Tides Work…
Tapping Tidal Energy
A Tidal Dam Works Well…
A Tidal Dam Creates Problems…
Oceanography- Chapter 18
The Seafloor
Ocean Basin Features– Continental shelf-– Continental slope-– Abyssal plains-
Plate Boundary Structures- Mid ocean ridge-- trench
Mining the Ocean Floor
Salt has always been collected from the ocean water.
Now, we also collect oil, gas & minerals from the sea.
Life in the Ocean Energy Relationships:
- photosynthetic organisms capture the sun’s energy and make food using light energy, carbon dioxide, and water through _______________
- chemosynthetic organisms do not rely on sunlight; instead, they rely on ____________
Ocean LifePLANKTON NEKTON BENTHOS
-Tiny marine algae & animals-drift with currents
-actively swim -plants, algae & animals that live on the lowest levels of the ocean
Examples: Examples: Examples:
Pollution & Marine Life
ASTRONOMY!!!
Chapter 22: Sun-Earth-Moon System
Planet Earth Data
• Sphere: round, 3-D object whose surface at all points is the same distance from its center
• Axis: imaginary line around which earth spins• Rotation: spinning of Earth on its axis– causes day & night– 1 rotation takes 24 hours
Earth’s Magnetic Field
Earth’s Revolution
• Revolution: yearly orbit around the sun• Earth’s orbit is an ellipse
(NOT “circle” or “eclipse”)• Revolution around the sun takes 365 days
SEASONS
• Earth’s TILT on its axis causes the seasons
• Hemisphere tilted toward the sun receives more hours of sunlight & direct rays
Equinoxes & Solstices
Earth’s Moon
• The moon rotates on its axis and revolves around the earth once every 27.3 days.
• Because these two motions take the same amount of time, we only see ONE side of the moon.
Moon Phases
• Moon Phase: apparent change in the shape of the moon as seen from earth
• Depends upon the relative positions of the earth, sun and moon
• WAXING = more of the moon becomes visible• WANING = less of the moon becomes visible
Solar Eclipse- moon comes between the earth & sun, casts a shadow on earth
Lunar Eclipse- earth comes between the moon & sun, blocks sunlight from reaching moon
The Solar System• Collection of planets & other objects that orbit the sun
• Inner Planets (rocky, solid core)• Outer Planets (gaseous)
Size & Composition
Atmosphere Temperatures
Surface Features
Moons(number/names)
# of Earth Days to
Orbit the Sun
The Inner Planets
Size & Composition
Atmosphere Below the Atmosphere
Notable Features
Moons(number/names)
# of Earth Days to
Orbit the Sun
The Outer Planets
OTHER OBJECTS IN SPACE
• Comets (Cupids, Donner, Blitzen) orbit the sun
• Composed of dust and rock particles mixed in with frozen water and gases.
• The most well-known comet is Halley’s Comet. It is visible on Earth every76 years.
Meteors
• Meteoroids - A large rock traveling through space, composed of nickel and iron.
• Meteor – A meteoroid that reaches the earth’s atmosphere.
AKA: “shooting star”• Meteorite – A meteor that
hits the earth’s surface
• Asteroids – are pieces of rock that orbit the sun between Mars and Jupiter (The Asteroid Belt)… What are they doing there?
Stars and Galaxies
Chapter 24
Constellations
• Constellations – groups of stars that form patterns that look like familiar objects or characters
• Modern astronomers have divided the sky into 88 constellations
• Polaris is the North Star
• Circumpolar Constellations 5 constellations that circle Polaris and are visible all year long in the
Northern Hemisphere
Magnitude• Apparent Magnitude– Measure of the
amount of light received by earth
• Absolute Magnitude– Measure of amount of
light actually given off by a star
Distance to Stars
• Parallax– Apparent shift in the position of an object
when viewed from 2 different positions
• Light Year– Distance light travels in 1 year– Light travels FAST (300,000 km/s)
Star Temperature
The Sun• STATS:– Average, middle-aged, yellow star– Produces energy by fusing hydrogen into helium in
its core
• Layers & Atmosphere– Photosphere– Chromosphere– corona
Features of the Sun
• Sunspots, prominences, flares– All caused by the
intense magnetic field of the sun
H-R Diagram
Evolution of Stars
GALAXIES: large group of stars, gas, & dust held together by gravity
Elliptical Spiral Irregular
The Milky Way
• What you know as HOME• Spiral galaxy
Doppler Shift
• The Doppler Shift causes wavelengths of light coming from galaxies to be compressed or stretched– Used to determine whether objects are moving toward
or away from the earth
– Red Shift (appear to move away)– Blue Shift (appear to move toward object)