Earth Science NHSPE Preparation and Tutoring
Objectives • Objective 1: Students know the Sun is the major source of Earth’s energy, and provides the energy driving Earth’s weather and climate. • Explain how solar energy powers the water cycle. • Explain how uneven heating of Earth’s surface determines weather and climate patterns. • Objective 2: Students know the composition of Earth’s atmosphere has changed in the past and is changing today. • Explain how variations in the ozone layer affect the amount of ultraviolet radiation entering the Earth’s atmosphere. • Describe how life forms have affected the composition of the atmosphere over time. • Describe how natural events have affected the composition of the atmosphere over time (e.g., volcanoes and meteorites).
Objectives • Objective 3: Students understand the role of the atmosphere in Earth’s greenhouse effect. • Explain how the proportions of gases in the atmosphere affect weather and climate. • Identify sources of greenhouse gases. • Explain why a certain level of greenhouse effect is essential for life on Earth. • Objective 4: Students know convection and radiation play important roles in moving heat energy in the Earth system. • Explain how the processes of radiation, conduction, and convection occur in the atmosphere. • Explain how the processes of radiation, conduction, and convection affect weather and climate. • Objective 5: Students know Earth’s rotation affects winds and ocean currents. • Identify that wind and ocean currents form global patterns based on Earth’s rotation.
Key Info • Earth's atmosphere is a very thin layer wrapped around a very large planet. • Two gases make up the bulk of the earth's atmosphere: nitrogen (78%), and oxygen (21%). Various trace gases make up the remainder. • Based on temperature, the atmosphere is divided into four layers: the troposphere, stratosphere, mesosphere, and thermosphere. • Energy is transferred between the earth's surface and the atmosphere via conduction, convection, and radiation. • Ocean currents play a significant role in transferring this heat poleward. Major currents, such as the northward flowing Gulf Stream, transport tremendous amounts of heat poleward and contribute to the development of many types of weather phenomena.
Interaction-Sun and Earth • More than 99% of the Earth’s energy comes from the Sun in the from of visible light. • The Earth also sends energy back into outer space, mostly as infrared radiation. • On average, this transfer of this incoming and outgoing energy is nearly equal. • Where does the Sun’s energy go on Earth? • 30% is reflected back to space. • 19% of the incoming solar energy is absorbed by the Earth’s atmosphere and clouds. • The remaining 51% is absorbed by the Earth’s surface. • Most of the energy that reaches the Earth’s surface is in the form of visible light.
Energy – From Earth to Where? • To maintain equilibrium, the Earth returns the energy it receives from the Sun back to space as infrared light. • Only 6% of the energy goes directly from the Earth’s surface to space. • About 15% of the Earth’s surface energy is absorbed by water vapor, carbon dioxide and other gases in the atmosphere. (greenhouse effect) • The remainder of Earth’s surface energy is transferred to the atmosphere in a more complex exchange involving sensible and latent heat. • Sensible heat is the energy associated with the temperature of a body. A warm surface will be at a higher temperature. Sensible heat flows from the surface to the atmosphere via convection (air circulations) or conduction (molecular motion). • Latent heat is the energy associated with phase changes. In the atmosphere, water vapor condenses forming clouds and precipitation. This releases latent heat to the atmosphere. Latent heat also flows from the atmosphere to the surface during evaporation. Evaporation cools the atmosphere. • So, infrared radiative transfer combined with flux of sensible and latent heat provides the energy to the atmosphere. This energy, which ultimately originated from the Sun, drives all of Earth’s weather and climate.
What Does The Sun Energy Do On Earth? • Powers the water cycle. (and many of the other biochemical cycles). • Warms the atmosphere and surface • Drives weather and climate through the uneven heating of the Earth’s surface. • Provides needed energy for photosynthesis in plants
The Water Cycle • Water: essential for life on earth. It is recycled through the water or hydrologic cycle. • Amount of water on earth remains nearly constant and is continually recycled through time. • Water molecules may remain in one form for a very long period of time and in other forms for very short times. • Remember, this is all driven by energy from the sun!
Water Cycle Processes • Evaporation: changing of water from a liquid to a gas • Condensation: changing of water from a gas to a liquid • Sublimation: changing of water from a solid to a gas • Precipitation: water molecules condense to form drops heavy enough to fall to the earth's surface
Water Cycle Processes • Transpiration: moisture is carried through plants from roots to leaves, where it changes to vapor and is released to the atmosphere • Surface runoff, the flowing of water over the land from higher to lower ground • Infiltration: the process of water filling the porous spaces of soil • Percolation: groundwater moving in the saturated zone below the earth's surface
Atmosphere –Its Role • Atmosphere Role: protects the Earth’s surface from the sun’s radiation and helps regulate the temperature of the Earth’s surface. • What is the atmosphere? • A mixture of gases the surrounds a planet. • All weather on Earth occurs in the atmosphere and it is essential to life.
Atmosphere Composition • Composition of the atmosphere: • Nitrogen 78% • Oxygen 21% • Carbon dioxide 0.03% • Other gases 0.17% • Water vapor (variable) 1-3%
Layers of the Atmosphere(The Most Important Ones) • Troposphere: closest to the Earth’s surface and where weather occurs. You can find the majority of the water vapor and carbon dioxide here (hey, it’s the greenhouse glass!) • Stratosphere: from the top of the troposphere (known as the tropopause) to altitude of 50km. Ozone lives here (well almost all of it). • Mesosphere: from the stratopause (the top of the stratosphere) to altitude of 80km. Coldest temperatures in the atmosphere! • Thermosphere: Almost to the top. The only thing beyond is the ionosphere (aurora borealis zone) and exosphere (transition to space). Nitrogen and oxygen absorb solar radiation here.
Greenhouse Gases and the Greenhouse Effect • Greenhouse gases: carbon dioxide, methane, water vapor • Importance of greenhouse gases: these gases help keep some of the radiation from going back to space. They help regulate the temperature of Earth and keep it habitable for life. • Note: Interference from humans can cause increases of greenhouse gases in the atmosphere. When this happens, the Earth may get too hot!
Sources of Greenhouse Gases • Naturally through the biochemical cycles (Water cycle, carbon cycle, nitrogen cycle, etc), volcanes, etc. • Human interference through CFC emissions and industrial activities.
Atmosphere & Ocean • Oceans cover nearly three-quarters of the earth's surface and play an important role in exchanging and transporting heat and moisture in the atmosphere. • Most of the water vapor in the atmosphere comes from the oceans. • Most of the precipitation falling over land finds its way back to oceans. • About two-thirds returns to the atmosphere via the water cycle. • You may have figured out by now that the oceans and atmosphere interact extensively. Oceans not only act as an abundant moisture source for the atmosphere but also as a heat source and sink (storage).
Atmosphere-Ocean • Ocean currents play a significant role in transferring this heat poleward. Major currents, such as the northward flowing Gulf Stream, transport tremendous amounts of heat poleward and contribute to the development of many types of weather phenomena. They also warm the climate of nearby locations. Conversely, cold southward flowing currents, such as the California current, cool the climate of nearby locations.
Energy Heat Transfer • Energy is transferred between the earth's surface and the atmosphere via conduction, convection, and radiation. • Conduction:process by which heat energy is transmitted through contact with neighboring molecules. • Convection transmits heat by transporting groups of molecules from place to place within a substance. Occurs in fluids such as water and air, which move freely. • Radiation: the transfer of heat energy without the involvement of a physical substance in the transmission. Radiation can transmit heat through a vacuum.
Conduction • Air and water are relatively poor conductors. • Most energy transfer by conduction occurs right at the earth's surface. • At night, the ground cools and the cold ground conducts heat away from the adjacent air. • During the day, solar radiation heats the ground, which heats the air next to it by conduction.
Convection • In the atmosphere, convection includes large- and small-scale rising and sinking of air masses and smaller air parcels. • These vertical motions effectively distribute heat and moisture throughout the atmospheric column and contribute to cloud and storm development (where rising motion occurs) and dissipation (where sinking motion occurs).
Convection Cells • Convection cells distribute heat over the whole earth. • Consider a simplified, smooth earth with no land/sea interactions and a slow rotation. Under these conditions, the equator is warmed by the sun more than the poles. The warm, light air at the equator rises and spreads northward and southward, and the cool dense air at the poles sinks and spreads toward the equator. As a result, two convection cells are formed. • Meanwhile, the slow rotation of the earth toward the east causes the air to be deflected toward the right in the northern hemisphere and toward the left in the southern hemisphere. This deflection of the wind by the earth's rotation is known as theCoriolis effect.
Radiation • Energy travels from the sun to the earth by means of electromagnetic waves. • The shorter the wavelength, the higher the energy associated with it. • Most of the sun's radiant energy is concentrated in the visible and near-visible portions of the spectrum. Shorter-than-visible wavelengths account for a small percentage of the total but are extremely important because they have much higher energy. These are known as ultraviolet wavelengths.
2. Earth’s Composition & Structure • Diagram
Objectives • Objective 1: Students know how successive rock strata and fossils can be used to confirm the age, history, and changing life forms of the Earth, including how this evidence is affected by the folding, breaking, and uplifting of layers. • Explain the basics of the process of fossil formation. • Apply the principles of superposition to relative dating of rock layers. • Describe the process of absolute dating. • Sequence the age, history, and changing life forms of Earth using strata and fossil evidence. • Describe how folding, breaking, and uplifting of strata complicate geological evidence. • Objective 2: Students understand the concept of plate tectonics including the evidence that supports it (structural, geophysical and paleontological evidence). • Describe how convection in Earth’s mantle has changed the locations + shapes of continents based on tectonic plate movement. • Identify the evidence for seafloor spreading. • Identify the three major types of tectonic plate boundaries.
Objectives • Objective 3: Students know elements exist in fixed amounts and move through solid earth, oceans, atmosphere and living things as part of biogeochemical cycles. • Explain how matter and energy are transferred chemically through systems that include living and non‐living components. • Objective 4: Students know processes of obtaining, using, and recycling of renewable and non‐renewable resources. • Identify the differences between renewable and non‐renewable resources. • Explain how recycling reduces the rate of depletion of nonrenewable resources. • Identify the processes used to obtain natural resources (e.g., mining, oil production, water, and agriculture). • Objective 5: Students know soil, derived from weathered rocks and decomposed organic material, is found in layers. • Describe the structure of soil, its components, and its formation
Fossils • Different rock layers contain different fossils (key to dating the geologic past) • Fossils: the remains of animals or plants that lived in a previous geologic time • Paleontology: the study of fossils • Fossils provide information to the relative and absolute ages of rocks, as well as provide clues to past geologic events, climates, and evolutiom
Fossilization • Generally, only the hard parts of organisms become fossils. Fossilization processes are: • Mummification • Amber: hardened tree sap • Tar Seeps • Freezing: almost completely preserved • Petrification: replica of the original organism
Fossil Types • Trace fossil: a fossilized mark that formed in sedimentary rock by the movement of an animal on or within soft sediment • Index fossil: fossils that occur only in rock layers of a particular geologic age (used to determine the relative age of rock layers) • Must be present in rocks scattered over a large region • Must have features that clearly distinguish it from other fossils • Organism must have lived during a short span of geologic time • Must occur in fairly large numbers within the rock layers
Rock Cycle • Rocks: naturally occurring aggregates of one or more minerals. • Composed of material that has been present on Earth since it first formed – excluding that material which has been delivered by meteorites • Rock Cycle: a model that illustrates the changes to rocks that have taken place through time. • Rocks are recycled into other rocks through processes which occur in mainly two locations; at or near Earth’s surface such as weathering, erosion, and deposition; and deep below the surface such as melting and increased heat and pressure. Most rocks are formed from other rocks and a “rock” may take more than one path through the rock cycle.
Rock Cycle and Rock Types • Metamorphic rock: metamorphic rock would need to experience an increase in temperature to the point of melting it, creating magma. • Eventually this magma body would enter an environment where the heat contained would transfer from it (cooling) and the process of solidification (crystallization) occurs. This rock is now classified as an igneous rock. • Igneous rock: several more changes must occur in order to turn this igneous rock into a sedimentary rock. • The igneous rock needs to be subjected to the agents of weathering and erosion, which over geologic time creates pieces or fragments of rock called sediment. As this sediment piles up, compaction and cementation turn the loose sediment into a solid rock through the process of lithification. This rock is now classified as a sedimentary rock. • Continuing clockwise this sedimentary rock will become a metamorphic rock with the addition of heat and pressure causing a partial melting of some of the minerals in the sediment. This process is referred to as metamorphism and results in creation of a metamorphic rock. The straight arrows within the rock cycle diagram indicate that any one rock type can turn into any other rock type by passing through several common processes.
Rocks and Minerals • Key Points: • Fossils • Superposition • Absolute dating • Rock Types • Mineral Information
External Forces • Processes that wear the Earth’s surface down • 1. Weathering: the breaking down of rocks into smaller pieces (assists in the formation of soil) • Physical weathering • Chemical weathering • 2. Erosion: the process by which rock material at Earth’s surface is removed and carried away • Gravity and water • Glacier • Wind
Physical Weathering • Rock is broken into smaller fragments by physical agents • Example: water seeps into cracks, in a rocks and freezes, the water expands, breaking the rock apart • Example: roots of plants growing in cracks can also force rocks apart
Chemical Weathering • The breaking down of rocks through changes in their chemical make-up • Changes take place when rocks are exposed to air or water • Example: rainwater + carbon dioxide = weak acid that dissolves certain minerals in rocks causing rocks to fall apart • Example: oxygen + water + iron in rocks = iron into rust, crumbles easily
Erosion • Gravity and water: gravity moves water downhill, running/flowing water erodes rock material • Example: Grand Canyon • Glaciers: masses of ice that from in places where more snow falls in winter than melts in summer • Glacier moves downhill slowly, grinding and removing rock material • Wind: dry desert areas, sand grains blown along by the wind scrape and scour rock outcrops, slowly carving them into unusual shapes
Check for Understanding • Erosion is the process by which rocks at the Earth’s surface • A. Are removed and carried away • B. Crumble and decay • C. Turn into rust • D Melt to form magma
Internal Forces • Processes that shape the Earth’s surface. Produces: • Mountains: produced by faulting and folding • Earthquakes: produced by strong vibrations along faults • Volcanoes: a hole in Earth’s crust through which lava flows from underground; lava cools to form solid rock • Plains: broad flat regions found at low regions; often made of layered sedimentary rocks that were formed underwater and slowly raised above sea level • Plateaus: large areas of horizontally layered rocks with higher elevations than plains; formed by either a large block of crust rising up along faults, or being gradually uplifted without faulting, or built up by lava flows
Folding • Forces in Earth’s crust press rocks together from the sides, bending the layers into folds. The land is squeezed into upfolds and downfolds, forming ridges and valleys.
Faulting • Occurs when forces in the crust squeeze or pull rock beyond its capacity to bend or stretch. The rock then breaks and slides along a crack or fracture, called a fault, relieving the stress in the crust
Plate Tectonics • Theory that explains how internal forces that shape the Earth’s crust move and work. • Movements cause mountain building, volcanic activity, and earthquakes along the plate edges • Earth’s crust is divided into multiple plates that slowly move. • Divergent plates: plates that are moving away from each other • Transform plates: plates that are sliding past each other • Convergent plates: plates that collide
How Plate Tectonics Work • Plate motions caused by heat circulating in Earth’s mantle (the thick zone of rock beneath the crust)
How Plate Tectonics Work • Continental plate collision produces mountain ranges (ex. Himalayas) • Plates sliding past each other produce fault zones and earthquakes (ex. San Andreas Fault) • Plates spreading apart produce ocean basins • Continental drift: large continents are broken into smaller landmasses that move away from each other. • (Have you ever heard of Pangaea?)