Earth Science SOL Review ES 1 1. Mass is measured with a scale. Volume of solids can be measured with the water displacement method in a graduated cylinder. Density is then calculated with the formula: Density = Mass/ Volume 2. Bar and line graphs are constructed with the independent variable as the X-axis and the dependent variable as the Y-axis. 3. Graphs should the trends in data and should be interpreted to show relationships in the data. 4. Map scales relate distances on the map to distances on the Earth’s surface. A map with a larger denominator is the smaller scale map. A map with a smaller denominator is a larger scale map. 5. Topographic maps contain information about elevation. This information allows us to calculate the relief (difference in elevation) and the slope (Relief/distance) between two points. 6. Topographic profiles are constructed to show the change in elevation between two points. You should be able to construct and interpret a profile from a topographic map. 7. Satellite imagery and topographic maps are two- dimensional models that provide information about the three dimensional Earth features. These images contain information related to geographic as well as human structures and changes to the land surface. Satellite imagery can be used to study the changes on the Earth’s surface over time. 8. Grid systems of latitude and longitude are used to define locations and directions on maps, globes, and charts. 9. Latitude shows position north or south of the Equator (the reference line for latitude). The Equator divides the northern and southern hemispheres. Maximum value for latitude is 90o North or South. 10. Longitude shows position east of west of the Prime Meridian (reference line for longitude). The Prime Meridian divides the eastern from the western hemispheres. Maximum value for longitude is 180o . 11. Latitude and Longitude lines are measured in degrees. Each degree is divided into 60 minutes, and each minute into 60 seconds. 12. Each point on Earth has a unique latitude and longitude value. No points on Earth have the same latitude and longitude. This allows places to be located on a map. Earth Science SOL review points Page 1 ES 2 13. The nature of science tries to make the world understandable. Science is based on evidenceboth observational and experimental. 14. Science is a blend of logic and innovation. Scientific ideas are durable yet subject to change as new data are collected. 15. Scientists try to remain objective and engage in peer review to help avoid bias. 16. Earth is a dynamic system and all atmospheric, lithospheric, and hydrospheric processes interrelate and influence one another. 17. A hypothesis is a tentative explanation for a set of facts and can be tested by further investigation. Only hypotheses that are testable are valid. A hypothesis can be supported, modified, or rejected based on collected data. Experiments are designed to test hypotheses. 18. Predictions may only be made using scientific data and data analysis. 19. Scientific theories are systematic sets of concepts that offer explanations for observed patterns in nature. Theories provide frameworks for relating data and guiding future research. Theories may change as new data becomes available. Any valid scientific theory has passed tests designed to invalidate it. 20. There can be more that one scientific explanation for phenomena. However, with competing explanations, generally one idea will become accepted as new tools, new observations, and verified data become available. 21. Changing the independent variable will generally change the outcome of the experiment. The independent variable is the one variable manipulated during the experiment. 22. The dependent variable is the data collected during the experiment. The data should change if the independent variable was changed. 23. Scientific laws are generalizations of observational data that describe patterns and relationships. Laws may change as new data become available. ES 3 24. The Earth is the third planet from the Sun and has one moon. The planets in order from Sun out are: Mercury, Venus, Earth, Mars, (Asteroid Belt), Jupiter, Saturn, Uranus, Neptune, and dwarf planet Pluto. 25. Water exists on Earth as a solid (ice), liquid, or gas (water vapor) due to Earth’s position in the solar system. 26. The Earth rotates on its axis. This creates day and night. 27. The Earth revolves around the sun tilted on it’s axis. The Earth’s tilt points to the same place in the sky. This tilt causes the angle of sunlight and the length of daylight hours to change during the year. In summer the sun is higher in the sky and above the horizon longer, making it hotter. In winter the sun is lower in the sky and above the horizon less, making it colder. 28. At the summer solstice the sun is located at 23.5oN(Tropic of Cancer). At the winter solstice the sun is located at 23.5oS (Tropic of Capricorn). During the vernal (spring) and autumnal equinoxes the sun is located on the equator. Earth Science SOL review points Page 2 29. The moon revolves around the Earth. This creates the moon phases. 30. A solar eclipse occurs during a new moon when the moon gets between the Sun and Earth. 31. A lunar eclipse occurs during the day when the Earth gets between the Sun and the moon. 32. An solar or lunar eclipse can only occur when the sun-earth-moon align in the same plane. This does not occur every month. 33. There are several ideas on the formation of the moon. They include the fission hypothesis, coformation hypothesis, capture hypothesis, and impact hypothesis. The impact hypothesis is currently the most accepted. Earth Science SOL review points Page 3 34. The tides are the rise and fall of water level caused by the gravitational pull of the moon and sun. The moon has a bigger effect on tides. Spring Tides Neap Tides 35. The Sun consists mainly of Hydrogen gas. The Sun makes its energy from nuclear fusion of hydrogen to helium. 36. There are two types of planets in the solar system. The four inner (terrestrial) planets consist mostly of solid rock. The four outer planets are gas giants, consisting of thick outer layers of gaseous materials with small rocky cores. 37. The inner planets have a greater density (3.9-5.5 g/cm3) than the outer planets . (.7-1.7 g/cm3) The core of the inner planets is more metallic and the core of the outer planets is more rocky. The crust of the inner planets is rocky, the crust of the outer planets is frozen gases. The atmosphere of the inner planets (except Mercury- no atmosphere) is heavier gases. The atmosphere of the outer planets is H, CH4, and lighter gases. 38. The inner planets tend to rotate slower than the outer planets. 39. The dwarf planet, Pluto, has an unknown composition but appears to be solid. It is part of the Kuiper Belt, due to the similarity to these objects. 40. Moons are natural satellites of planets and vary widely in composition. 41. Comets orbit the sun and consist of frozen gases and dust particles. The tail of the comet forms as the comet gets closer to the sun and will point away from the sun. 42. A meteoroid is debris outside the Earth’s atmosphere; a meteor is debris within the Earth’s atmosphere; and a meteorite is debris that has hit the Earth’s surface. 43. Asteroids are usually leftover debris from the formation of the solar system, or from the collision of other asteroids. Most asteroids orbit the Sun between Mars and Jupiter. Earth Science SOL review points Page 4 44. The atmosphere of Venus is most CO2 and is very dense. The atmosphere of Mars is very thin and also made of CO2. 45. Much of our knowledge about the solar system is a result of space exploration efforts. Space exploration series include: Sputnik (1957) Russian satellite- first artificial satellite in space. Mercury( 1959-1963) one manned flights. First in space Alan Shepard, first to orbit earth John Glenn. Gemini (1965-1966) two manned flights. Space walks, docking in space. Apollo (1969-1972) three manned mission to the moon. Apollo 11 first to land in 1969. Neil Armstrong, then Buzz Aldrin walked on moon (Michael Collins remained orbiting moon). Last mission in 1972. Space Shuttle International Space station Voyager (1980’s) unmanned probes to outer planets Galileo (1995) unmanned probe reaches Jupiter Cassini (2004) unmanned probe reaches Saturn Hubble Space Telescope (1990 launch) ES 4 46. A mineral is a naturally occurring, inorganic, solid substance with a definite chemical composition and crystal structure and can be identified based on specific chemical and/or physical properties. 47. Most minerals are compounds. Some minerals are pure elements found as minerals. Many elements (especially metals like Al, Fe, Si) react with other elements and are rarely found as minerals in nature. 48. The four most abundant elements in the Earth’s crust are oxygen (46.6%), Silicon (27.7%, Aluminum (8.1%), and Iron (5.0%). The most abundant group of minerals is the silicates, which contain Silicon, Oxygen, and other elements. Common silicates include feldspar and quartz. 49. Mineral can be grouped by similar chemical patterns. Common chemical families are oxides (metals with oxygen), sulfides (metals with sulfur), and carbonates (metals with CO3). Common carbonates are calcite and dolomite. Common oxides are hematite and magnetite. 50. Mineral properties include hardness, cleavage, fracture, color, streak, and luster. 51. Some minerals have unique properties such as magnetism, double refraction, fluorescence, and radioactivity. 52. Hardness, cleavage, fracture, and crystal pattern are determined by the way the atoms are arranged in the mineral. 53. Common minerals seen in Virginia include quartz, feldspar, mica, and calcite. Common ore minerals include pyrite, magnetite, hematite, and galena. Some minerals like graphite are used in pencils and as a lubricant. 54. Minerals have long been used by man in construction, as sources of metal, and as gems. ES 5 55. Rocks are identified on the basis of mineral composition and texture. 56. The three main types of rocks are igneous, sedimentary, and metamorphic. 57. The rock cycle is the process by which all rocks are formed and how basic earth materials like rocks are recycled through time. Earth Science SOL review points Page 5 58. Igneous rock forms from molten rock that cools and hardens either below or on Earth’s surface. Extrusive igneous rocks have small or no crystals, resulting in fine-grained or glassy textures and include pumice, obsidian, and basalt. Intrusive igneous rocks have larger crystals and a coarser texture and include granite. 59. Sedimentary rocks may be formed either by rock fragments or organic matter being bound together or by chemical precipitation. Clastic sedimentary rocks are made up of fragments of other rocks and include sandstone, conglomerate, and shale. Non-clastic sedimentary rocks include limestone and rock salt. 60. Metamorphic rocks form when any rock is changed by the effects of heat, pressure, or chemical action. Foliated metamorphic rocks have bands of different minerals and include slate, schist, and gneiss. Unfoliated metamorphic rocks have little or no banding and are relatively homogenous throughout and include marble and quartzite. ES 6 61. Resources are limited and are either renewable or nonrenewable. 62. Renewable resources can be replaced by nature at a rate close to the rate at which they are used. Renewable resources include vegetation, sunlight, and surface water. 63. Nonrenewable resources are replenished very slowly or not at all. Nonrenewable resources include coal, oil, and minerals. 64. Fossil fuels are nonrenewable and may cause pollution, but they are relatively cheap and easy to use once they are extracted. 65. Extraction and use of any resource carries an environmental cost that must be weighed against economic benefit. 66. In Virginia, major rock and mineral resources include coal for energy, gravel and crushed stone for road construction, silica for electronics, zirconium and titanium for advanced metallurgy, and limestone for making concrete. 67. Clean water resources, while renewable, are directly impacted by human activity through extraction and pollution. 68. Coal forms from dead plants. Earth Science SOL review points Page 6 69. The sequence of coal goes plants in swamp compresses, peat, lignite, bituminous, anthracite. As this sequence progresses the relative per cent of carbon increases. ES 7 70. Virginia has a billion year long tectonic and geologic history. 71. There are five main physiographic provinces in Virginia. They are (from east to west) the Atlantic Coastal Plain, Piedmont, Blue Ridge, Valley and Ridge, and Appalachian Plateau. 72. Virginia’s five physiographic provinces were produced by past episodes of tectonic activity and continuous geologic activity. Each province has unique physical characteristics resulting from its geologic past. 73. The Coastal Plain is a flat area of young, unconsolidated sediments underlain by older crystalline basement rocks. These layers of sediment were produced by erosion of the Appalachian Mountains and Piedmont and then deposited on the Coastal Plain when sea levels were higher in the past. 74. The Piedmont is an area of rolling hills underlain by mostly ancient igneous and metamorphic rocks. The igneous rocks are the roots of volcanoes formed during an ancient episode of subduction that occurred before the formation of the Appalachian Mountains. 75. The Blue Ridge is a high ridge separating the Piedmont from the Valley and Ridge Province. The billion-year-old igneous and metamorphic rocks of the Blue Ridge are the oldest in the state. Earth Science SOL review points Page 7 76. The Valley and Ridge province is an area with long parallel ridges and valleys underlain by ancient folded and faulted sedimentary rocks. The folding and faulting of the sedimentary rocks occurred during a collision between the African and North American Plates. The collision, which occurred in the late Paleozoic Era, produced the Appalachian Mountains. 77. The Appalachian Plateau has rugged, irregular topography and is underlain by ancient, flat-lying sedimentary rocks. The area is actually a series of plateaus separated by faults and erosional down-cut valleys. Most of Virginia’s coal resources are found in the plateau province. 78. Geologic processes produce characteristic structures and features. 79. Earth consists of a solid, mostly iron inner core; a liquid, mostly iron outer core; a crystalline but largely plastic mantle; and a rocky, brittle crust. 80. Earth’s lithosphere is divided into plates that are in motion with respect to one another. The lithosphere is composed of the crust and upper portion of the mantle. There are two different types of lithospheres — oceanic and continental — that have very different physical and mineralogic characteristics. The ocean lithosphere is relatively thin, young, and dense. The continental lithosphere is relatively thick, old, and less dense. 81. Most large scale, high-energy events of geologic activity (e.g., earthquakes, volcanoes, and mountain building) occur as a result of relative motion along plate boundaries. Earth Science SOL review points Page 8 82. Plate motion occurs as a consequence of convection in Earth’s mantle, including upwelling of material from the deep mantle in rift zones, the lateral movement of tectonic plates, and the sinking dense, old plates at subduction zones. 83. The proof of plate tectonics is the age of oceanic crust (youngest at the MOR) and the paleomagnetic reversal patterns matching on both sides of the MOR. 84. Relative plate motions and plate boundaries are convergent (subduction and continental collision), divergent (seafloor spreading), or transform. Major features of convergent boundaries include collision zones (folded and thrust-faulted mountains) and subduction zones (volcanoes and trenches). Major features of divergent boundaries include mid-ocean ridges, rift valleys, fissure volcanoes, and flood lavas. Major features of transform plate boundaries include strike-slip faults. 85. Earthquake activity of varying energy levels is associated with all plate boundaries. All plate boundaries may have shallow earthquakes, but most deep focus earthquakes are associated with subduction boundaries. 86. A volcano is an opening where magma erupts onto Earth’s surface. Most volcanic activity is associated with subduction, rifting, or seafloor spreading. Hot spot volcanic activity, such as the Hawaiian Islands, is not related to a plate boundary but derived from a deep, localized heat source. 87. A fault is a break or crack in Earth’s crust along which movement has occurred. Normal faults are created by tension. Reverse faults are created by compression. A low angle reverse fault is called a thrust fault. Strike-slip faults are caused by shearing. Earth Science SOL review points Page 9 88. Folds are caused by compression. Upward folds are called anticline. Downward folds are called synclines. 89. Plate tectonic processes serve as the major driver of the rock cycle. Plate tectonics drive the evolution of Earth’s surface features and materials by fractionating material by chemical, mineralogic, and physical properties. Continental drift is a consequence of plate tectonics. 90. Weathering, erosion, and deposition are interrelated processes. Weathering is the process by which rocks are broken down chemically and physically by the action of water, air, and organisms. Erosion is the process by which Earth materials are physically incorporated by moving water, ice, or wind for transportation. Deposition is the process by which Earth materials carried by wind, water, or ice settle out and are left in a location when energy levels decrease. The size of the material deposited is proportional to the available energy of the medium of transport. Earth Science SOL review points Page 10 ES 8 91. Soil is formed from the weathering of rocks and organic activity and is composed of loose rock fragments and clay derived from weathered rock mixed with organic material. 92. Karst topography is developed in areas underlain by carbonate rocks, including limestone and dolomite. Karst topography includes features like caves and sinkholes and forms when limestone is slowly dissolved away by slightly acidic groundwater. Where limestone is abundant in the Valley and Ridge province of Virginia, karst topography is common. Karst Topography Limestone 93. Permeability is a measure of the ability of a rock or sediment to transmit water or other liquids. Water does not pass through impermeable materials. A substantial amount of water is stored in permeable soil and rock underground. Earth Science SOL review points Page 11 94. Below the surface is an area where water and air fill available pore spaces. This area is called the zone of aeration. Below this is an area where only water fills all available pore spaces. This area is the zone of saturation. The water table is the top of the zone of saturation. 95. When water is pumped from the ground the water table is affected at the local level. This creates a cone of depression. Water will then flow in all directions to the well. The cone of depression may lower the water table and the well then may become dry. 96. Water is continuously being moved throughout the hydrologic cycle. Fresh water is necessary for survival and most human activities. Earth Science SOL review points Page 12 96. Earth’s fresh water supply is finite. Geologic processes, such as erosion, and human activities, such as water disposal, can pollute water supplies. 97. The three major regional watershed systems in Virginia lead to the Chesapeake Bay, the North Carolina sounds, and the Gulf of Mexico. North Carolina sounds Gulf of Mexico Watershed Chesapeake Bay Watershed 98. Coastal areas of Virginia are seeing salt water intrusion affecting their groundwater supply. Some is created by over pumping wells from near the sea. A large impact crater has caused some intrusion near Virginia Beach and the Eastern Shore of Virginia. 99. The groundwater supply of the Coastal Plain is “soft” with little dissolve mineral matter. Groundwater from the Valley and Ridge is “hard” due to higher amounts of dissolved mineral matter in the limestone filled valleys. Earth Science SOL review points Page 13 ES 9 100. The history of Earth and the ages of rocks can be investigated and understood by studying rocks and fossils. 101. Evidence of ancient, often extinct life is preserved in many sedimentary rocks. A fossil is the remains, impression, or other evidence preserved in rock of the former existence of life. Fossil evidence indicates that life forms have changed and become more complex over geologic time. Some ways in which fossils can be preserved are molds, casts, and original bone or shell. 102. Relative time places events in a sequence without assigning any numerical ages. Fossils, superposition, and cross-cutting relations are used to determine the relative ages of rocks. Absolute time places a numerical age on an event. Radioactive decay is used to determine the absolute age of rocks. 103. Life forms have become more complex through geologic time. 104. The age of Earth is 4.6 billion years. 105. In Virginia, fossils are found mainly in the Coastal Plain, Valley and Ridge, and Appalachian Plateau provinces. Most Virginia fossils are of marine organisms. This indicates that large areas of the state have been periodically covered by seawater. 106. The Geologic Time Scale arranges all Earths history into units of geologic time. The largest unit of geologic time is the eon. Eons are divided into era, eras into periods, and periods into epochs. All time before the Cambrian Period, Paleozoic Era, Phanerozoic Eon is called PreCambrian Time. 107. Paleozoic, Mesozoic, and Cenozoic Era (Phanerozoic Eon) fossils are found in Virginia. 108. Many mass extinctions have occurred in Earth’s past. Most are linked to global catastrophies (asteroid/comet impacts, volcanism, continental collisions, rapid climate changes). These have played a major role on extinctions and evolution. ES 10 109. The ocean is a dynamic system in which many chemical, biological, and physical changes are taking place. The oceans are an important source of food and mineral resources as well as a venue for recreation and transportation. Sea level falls when glacial ice caps grow and rises when the ice caps melt. Earth Science SOL review points Page 14 110. Most waves on the ocean surface are generated by wind. 111. There are large ocean current systems in the oceans that carry warm water towards the poles and cold water towards the equator. Most warm currents are found on the western side of the ocean basin (east side of continents). Most cold currents are found on the eastern side of the ocean basin (west side of continents). 112. Upwellings bring cold, nutrient-rich water from the deep ocean to the surface and areas of rich biological activity. 113. The tides are periodic rise and fall of water level caused by the gravitational pull of the moon and the sun. (see diagram with point 34) 114. The movement of continents through geologic time has influenced ice caps and ocean circulation over long periods of time. 115. The oceans’ resources are finite and should be utilized with care. 116. Algae in the ocean are an important source of atmospheric oxygen. 117. The ocean is the single largest reservoir of heat at Earth’s surface. The stored heat in the ocean drives much of Earth’s weather and causes climate near the ocean to be milder than climate in the interior of continents. 118. Convection is the major mechanism of energy transfer in the oceans, atmosphere and Earth’s interior. Earth Science SOL review points Page 15 119. The topography of the seafloor is at least as variable as that on the continents. Features of the seafloor that are related to plate tectonic processes include mid-ocean ridges and trenches (continental margins, trenches, and mid-ocean ridges). Other major topographic features of the oceans are continental shelves, continental slopes, abyssal plains, and seamounts. 120. The oceans are environmentally and economically important. Human activities and public policy have important consequences for the oceans. The impact of human activities, such as waste disposal, construction, and agriculture, affect the water quality within watershed systems and ultimately the ocean. Pollution and overfishing can harm or deplete valuable resources. 121. Estuaries, like the Chesapeake Bay, are areas where fresh and salt water mix, producing variations in salinity and high biological activity. Chemical pollution and sedimentation are great threats to the well-being of estuaries and oceans. 122. The Chesapeake Bay watershed may be affected by pollution that enters the bay from sources hundreds of miles away. Pollutants released anywhere in the Chesapeake Bay watershed will eventually reach the Bay and affect the food web. 123. Hurricanes form over warm ocean water 80o or higher. The water vapor evaporating from the ocean transfers vast quantities of energy into the atmosphere that can be released in the form of storms like hurricanes. ES 11 124. The composition of Earth’s atmosphere has changed over geologic time. Earth’s atmosphere is unique in the solar system in that it contains substantial oxygen. 125. The most primitive atmosphere was comprised of mainly helium and hydrogen. After the moon was formed, the early atmosphere contained mostly CO2, CO, and water vapor. These gases were released by volcanic eruptions (outgassing). This atmosphere was then modified by early photosynthetic life. 126. Early photosynthetic life such as cyanobacteria (blue-green algae) consumed carbon dioxide and generated oxygen. It was only after early photosynthetic life generated oxygen that animal life became possible. 127. Earth’s atmosphere is 21 percent oxygen, 78 percent nitrogen, and 1 percent trace gases. The composition of the atmosphere can change due to human, biologic, and geologic activity. Human activities have increased the carbon dioxide content of the atmosphere. Man-made chemicals have decreased the ozone concentration in the upper atmosphere. Volcanic activity and meteorite impacts can inject large quantities of dust and gases into the atmosphere. Earth Science SOL review points Page 16 128. The ability of Earth’s atmosphere to absorb and retain heat is affected by the presence of gases like water vapor and carbon dioxide. 129. The burning of fossil fuels releases more carbon dioxide and other greenhouse gases back into the atmosphere. This may cause the earth to warm up and has been known as global warming. 130. As global warming continues, polar ice caps and glaciers may melt. This will cause a global rise in sea level and affect Virginia’s coastal areas. ES 12 131. Energy transfer between Earth’s surface and the atmosphere creates the weather. 132. Weather and climate are different. Both weather and climate are measurable and, to a certain extent, predictable. Weather describes day-to-day changes in atmospheric conditions. Climate describes the typical weather patterns for a given location over a period of many years. Instrumentation is used to collect weather and climate data. 133. The four major factors affecting climate are latitude, elevation, proximity to bodies of water, and position relative to mountains. Earth’s major climatic zones are the polar, temperate, and tropical zones. Areas near the equator receive more of the sun’s energy per unit area than areas nearer the poles. 134. Earth’s surface is much more efficiently heated by the sun than is the atmosphere. The amount of energy reaching any given point on Earth’s surface is controlled by the angle of sunlight striking the surface and varies with the seasons. Earth Science SOL review points Page 17 135. Winds are created by uneven heat distribution at Earth’s surface and modified by the rotation of Earth. The Coriolis effect causes deflections of the atmosphere due to the rotation of Earth. Global wind patterns result from the uneven heating of Earth by the sun and are influenced by the Coriolis effect. Local winds are created by unequal heating of the surface at a local level. Land-sea breezes are an example of local winds. 136. Convection in the atmosphere is a major cause of weather. Convection is the major mechanism of energy transfer in the oceans, atmosphere, and Earth’s interior. 137. The jet stream is an upper troposphere level winds that can help intensify and guide weather patterns. The jet stream generally flows west to east, but may produce wave like patterns at it flows. 138. Weather instruments include the thermometer (temperature), barometer (air pressure), and psychrometer (dew point, and relative humidity). 139. Weather prediction are based on cloud type, temperature, and barometric pressure. 140. Weather maps are used to show location of different weather phenomena. Features on a weather map include fronts, isobars, and isotherms. 141. Air masses of large masses of air with similar properties of temperature and moisture. The five main air masses are maritime Tropical (mT)- moist and warm, continental Tropical (cT)- dry and warm, maritime Polar (mP)-moist and cold, continental Polar (cP)-dry and cold, and continental Arctic (cA)- dry and very cold. Earth Science SOL review points Page 18 142. Fronts are used to show the boundaries between opposing air masses. The main types of front are the cold front, warm front, stationary front, and the occluded front. Weather Front Symbols Warm front Cold front 143. Isobars connect points of equal air pressure. Areas of relatively higher air pressure are marked with a H on a weather map. Air is sinking and generally nice weather. Areas of relatively lower air pressure are marked with a L on a weather map. Air is rising and often produces cloud and precipitation. Areas of Low pressure are found around fronts. 144. The interaction of the Earth’s surface, oceans, and atmosphere and the heat transfer from one to the other heat regulate the earth’s heat budget. The three main methods of heat transfer are radiation, conduction, and convection. Earth Science SOL review points Page 19 145. Weather radar and satellite technology is an important tool in modern weather prediction and tracking of severe storms including hurricanes, tornadoes, and severe thunderstorms. This allows advanced warning in most cases, which can save lives and limit property damage. 146. The conditions necessary for cloud formation are air at or below dew point and presence of condensation nuclei. Cloud droplets can join together to form precipitation. 147. A tornado is a narrow, violent funnel-shaped column of spiral winds that extends downward from the cloud base toward Earth. A hurricane is a tropical cyclone (counterclockwise movement of air) characterized by sustained winds of 120 kilometers per hour (75 miles per hour) or greater. Enhanced Fujita Scale Saffir-Simpson Scale Earth Science SOL review points Page 20 ES 13 148. The universe is vast in size and very old. (14.6 billion years) 149. The Big Bang theory is our best current model for the origin of the universe. The Big Bang theory states that the universe began in a very hot, dense state that expanded and eventually condensed into galaxies. 150. Redshift is the shifting of the wavelength of light as stars move away from the earth or each other. This is proof of the Big Bang Theory. More proof comes from background microwave radiation that seems to be coming from all directions in space. Normal pattern on left and redshift on right. 151. The solar nebular theory is our best current idea for the origin of the solar system. The solar nebular theory explains that the planets formed through the condensing of the solar nebula. Earth Science SOL review points Page 21 152. Stars have a finite lifetime and evolve over time. The mass of a star controls its evolution, lifespan, and ultimate fate. Stars form by condensation and gravitational compression of interstellar gas and dust. 153. The Hertzsprung-Russell diagram illustrates the relationship between the absolute magnitude and the surface temperature of stars. As stars evolve, their position on the Hertzsprung-Russell diagram moves. 154. Galaxies are collections of billions of stars. The basic types of galaxies are spiral, elliptical, and irregular. Spiral galaxy Earth Science SOL review points Elliptical galaxy Irregular galaxy Page 22 155. The solar system is located in the Milky Way galaxy. 156. A light-year is the distance light travels in one year and is the most commonly used measurement for distance in astronomy. A light year is roughly 6 trillion miles. 157. Much of our information about our galaxy and the universe comes from ground-based observations across the electromagnetic spectrum. Much information about other planets comes from ground-based observations from Earth, but also from landers and orbiting spacecraft. Earth Science SOL review points Page 23 158. The life cycle of a star is related to the mass of the star. Stars like our Sun go through a different death sequence than more massive stars. 159. Nuclear fusion in the core of a star produces heavier elements through time. The presence of heavier elements on Earth supports the older age of the universe. 160. Elements like carbon and oxygen can be produced in the core of stars like our sun. Elements like iron and heavier elements form in supernovas. Earth Science SOL review points Page 24