CSET Multiple Subjects: Subtest 2b, Domain 3

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CSET Multiple Subjects Subtest 2: Science Domain 3: Earth and Space Science

Planets

-Divided into two main types: large, low-density gas giants and smaller, rocky terrestrials
-There are at least 341 identified planets, 8 of which are in the Solar System

Solar System

-4 terrestrials: Mercury, Venus, Mars, Earth
-4 gas giants: Jupiter, Saturn, Uranus, Neptune
-At least 5 dwarf planets: Ceres, Pluto, Makemake, Haumea, Eris

Venus

-Takes approx. seven and a half earth months for Venus to revolve around the sun
-Takes approx. eight earth months to rotate on its axis
-Therefore, a day on Venus is longer than a year
-Similar in size to Earth
-One of the few planets that rotate from east to west
-Similar in size to Earth
-Atmosphere is primarily composed of carbon dioxide
-This thick atmosphere traps heat due to the greenhouse effect
-The Magellan probe reached Venus in 1990 and provided detailed images of the planet

Comet

-A small Solar System body that orbits the Sun
-When close enough to the sun, exhibits a visible coma (atmosphere) or a tail, both primarily from the effects of solar radiation upon the comet's nucleus
-Comet nuclei are loose collections of ice, dust, and small rocky particles, measuring a few kilometers or tens of kilometers across
-Have a variety of different orbital periods, ranging from a few years, to hundreds of thousands of years, while some are believed to pass through the inner Solar System only once before being thrown out into interstellar space

Short-period comets

Thought to originate in the Kuiper Belt, or associated scattered discs, which lie beyond the orbit of Neptune

Long-period comets

-Believed to originate at a much greater distance from the Sun, in a cloud (the Oort cloud) consisting of debris left over from the condensation of solar nebula
-Comets are thrown from the outer planets or nearby stars, or as a result of collisions

Asteroids

-Sometimes called minor planets or planetoids
-Bodies—primarily of the inner Solar System—that are smaller than planets but larger than meteoroids, excluding comets
-The distinction between asteroids and comets is made by visual appearance; when discovered, comets show a perceptible coma while asteroids do not

Earth

-Travels in an orbit that is slightly elliptical (oval), and so the distance from the sun ranges from 91.5 to 94.5 million miles
-Its daily rotation deforms the earth to a flattened spheroid, with a polar radius slightly less than the equatorial radius
Locations of the surface are described by a grid of latitude and longitude lines

Gravity and inertia

-Both gravity and inertia work together to keep planets in orbit around the sun
-Inertia makes a planet travel in a straight line
-By definition, inertia is the tendency of a moving object to stay in a straight line or a stationary object to remain in place
-However, the power of the sun's gravity pulls the planets toward the sun
-The sun's gravity pulls the planets while their inertia keeps them moving forward in an elliptical orbit around the sun
-The strength of gravity in our solar system depends on both the masses of the celestial objects and the distance between them
-Gravity helps to explain the tides on earth
-Without inertia, a planet would be pulled into the sun

Weight and mass

-Gas giants Jupiter, Saturn, Uranus and Neptune have diameters far larger than Earth's and have far greater masses
-An individual weighing 200 lbs on Earth would weigh more on a larger planet
-Weight is a function of gravity

Latitude

The degrees north or south of the equator

Longitude

The degrees east or west of the prime meridian through Greenwich, England

Moon

-Travels around the earth each month
-Distance from the earth averages 237,000 miles
-Has rugged topography formed billions of years ago by volcanic eruptions and meteorite impacts
-Mass is 1/6th that of Earth

Phases of the moon

-New moon occurs when the moon sets at sunset
-Then the moon is between the earth and the sun, so we see only the dark half of the moon
-Each night, the moon sets a few minutes later and we perceive more of its illuminated half
-After the moon has waxed through crescent, quarter, and gibbous phases, a full moon appears
-At that time, the moon rises at sunset, and we see all of its illuminated side
-Then the phase wanes gradually to another new moon
-There are approx. 29.5 days between each cycle

Eclipses

-Ancient astronomers found that eclipses occurred periodically and learned to predict them accurately
-Lunar and solar

Lunar eclipse

-Darkens the moon as the earth passes between it and the sun, casting a shadow on the moon
-An eclipse of the moon may be seen from anywhere the moon is visible, about half of the earth

Solar eclipse

-Takes place when the moon passes between the earth and the sun, with the moon blocking the sunlight for about two minutes
-A total eclipse of the sun may be seen only from a small zone on the earth

Sun

-A huge ball of incandescent gases
-Its mass is more than 300,000 times that of the earth
-Principal constituents of the sun are the lightest elements, hydrogen and helium
-Under solar conditions, those gases are undergoing nuclear fusion to heavier elements with the increase of prodigious quantities of energy
-The center of the sun may have a temperature of millions of degrees; the visible surface, the photosphere, is about 6000°C
-Sunspots are somewhat cooler disturbances in the photosphere
-Atmosphere is divided into the inner chromosphere with explosive prominences and the outer corona, a glowing halo visible only during a total eclipse
-Constantly emitting particles as a solar wind

Stars

-Bodies similar to the sun but immensely distant
-Closest stars are 4 light-years away
-Speed of light is 186,000 miles/second
-Distance to closest stars can be calculated by measuring the parallax, a slight shift in apparent position against the background of more distant stars as the earth travels around the sun
-Stars with the highest surface temperature appear blue, while stars with the lowest surface temperature appear red

Galaxies

-Huge systems of stars
-Milky Way is estimated to have 100 billion stars arranged in a great disk
---The sun is not at the center of the disk, but out toward the perimeter, and is revolving around the galactic center
-Neighboring Andromeda galaxy is about 20 million light-years away
-Galaxies of spiral, elliptical, and irregular form are speckled throughout the visible universe
-Largest telescope has detected galaxies to its limit of several billion light-years

The big bang theory of cosmology

-The spectra of distant objects display a red shift, which is interpreted as meaning that they are rapidly receding from us
-This apparent expansion of the universe has given rise to the big bang theory of cosmology, in which one primeval mass exploded about 12 billion years ago

Time zone

-A region of the earth that has uniform standard time, usually referred to as the local time
-Time zones are divided into standard and daylight saving (or summer)
-Daylight saving time zones (or summer time zones) include an offset (typically +1 hour) for daylight saving time
-Standard time zones can be defined by geometrically subdividing the earth's spheroid into 24 lunes (wedge-shaped sections), bordered by meridians, each 15° of longitude apart
-The local time in neighboring zones would differ by one hour
-15° = 1 hour of time

Seasons

-Result from the earth's axis being tilted to its orbital plane, NOT the result of the variation in the earth's distance to the sun (Because of its elliptical orbit, the earth as a whole is slightly warmer when away from the sun; this is because the Northern Hemisphere has more land than the Southern Hemisphere, and land warms more readily than sea)
-Axis tilt deviates by an angle of approximately 23.5 degrees
-Thus, at any given time during summer or winter, one part of the planet is more directly exposed to the rays of the sun
-This exposure alternates as the earth revolves in its orbit
-At any given time, regardless of season, the Northern and Southern Hemispheres experience opposite seasons

Seasonal weather differences between hemispheres

-Further caused by the elliptical orbit of the earth
-Earth reaches perihelion (the point in its orbit closest to the sun) in January, and it reaches aphelion (farthest point from the sun) in July
-Also depend on factors such as proximity to oceans or other large bodies of water, currents in those oceans, El Niño and other oceanic cycles, and prevailing winds

Seasons in the temperate and polar regions

-Seasons are marked by changes in the amount of sunlight, which in turn often cause cycles of dormancy in plants and hibernation in animals
-These effects vary with latitude and with proximity to bodies of water
-For example, the South Pole is in the middle of the continent of Antarctica and is therefore a considerable distance from the moderating influence of the southern oceans
-The North Pole is in the Arctic Ocean, and thus its temperature extremes are buffered by the water
-The result is that the South Pole is consistently colder during the southern winter than the North Pole during the northern winter
-The cycle of seasons in the polar and temperate zones of one hemisphere is opposite to that in the other; when it is summer in the Northern Hemisphere, it is winter in the Southern Hemisphere, and vice versa

Equinoxes

-Occur twice a year, when the tilt of the earth's axis is oriented neither from nor to the sun, causing the sun to be located vertically above a point on the equator
-The name derived from the Latin aequus (equal) and nox (night), because at the equinox, the night and day are equally long
-Happen at two specific moments in time (not a whole day) around March 20 and Sept. 22 each year

Winter solstice

-Occurs at the instant when the sun's position in the sky is at its greatest angular distance on the other side of the equatorial plane from the observer's hemisphere
-Depending on the shift of the calendar, the winter solstice occurs some time between Dec. 20 and Dec. 23 each year in the Northern Hemisphere, and between June 20 and June 23 in the Southern Hemisphere, during either the shortest day or the longest night of the year

Seasonal dates in the Northern Hemisphere

Geology

The science that describes and interprets the earth

Fields:
-Geomorphology (land forms)
-Petrology (rocks)
-Stratigraphy (layered rocks)
-Paleontology (fossils)

Uniformitarianism

-Method of using the present to interpret the past
-Processes occurring today are observed carefully and their effects are measured
-Then, geologists assume that similar effects in ancient rocks were caused by processes similar to those of the present

Example: Glaciation in early eras is indicated by ancient deposits with features very similar to those produced by present-day glaciers.

The rock cycle

-Rocks are placed into groups according to how they form (sedimentary, igneous, metamorphic)
-In the rock cycle, rocks change their shape and composition
-The rock cycle is the process in which one type of rock changes into another

Sedimentary rocks

-Composed of the fragments of other types of rocks
-Often deposited in distinct parallel layers
-Weather and erosion break down other rock types into sediments
-Over time, the sediments become cemented and compacted and form into sedimentary rocks
-The processes that form sedimentary rock occur at the surface of the earth and within bodies of water
-Cover 75 to 80% of the earth's land area
-Classified by the source of their sediments
-Conglomerates are sedimentary rocks containing large fragments of other rock material
-Sandstone is another example
-Texture is important in classifying clastic sedimentary rocks
-Chemical sedimentary rocks form when dissolved mineral solutions crystalize out of lakes and oceans
-Rock salt (formed by sodium chloride) and limestone (formed from calcium carbonate) are examples of chemical sedimentary rocks
-Limestone can contain organic or once-living matter and can record the history of that matter's formation in features such as strata, fossil evidence, and ripple marks

Igneous rocks

-Classified according to composition and texture
-Form when magma or lava cools and solidifies
-Depending on the rate of cooling, some igneous rocks can contain visible crystals, while others can appear glassy
-Temperature, pressure, and composition explain the three ways magma can form since they affect the melting point of rock
-Igneous rock that cools beneath the earth's surface is called intrusive
-Examples of intrusive rock formations include plutons, dikes, and batholiths
-Igneous rock that forms on the earth's surface is called extrusive
-Examples of extrusive rocks include obsidian, basalt, and pumice

Metamorphic rocks

-Have undergone tremendous change from intense pressure and temperature
-All examples of the rock cycle can change into metamorphic rock
-Generally forms deep in the mantle as one type of rock changes into another
-The mineral composition of the rock changes when the minerals in the rock recrystallize
-Due to intense pressure, metamorphic rocks can show signs of bending and distortion
-Examples of metamorphic rocks include schist, marble, gneiss, and slate
-Usually classified according to texture and by chemical and mineral assemblage
-Make up a large part of the earth's crust

Coral reef

The result of the buildup of once-living things

Minerals

-Natural chemical compounds that are the crystals that make up rocks
-Each mineral has a specific composition or narrow range of composition
-The most abundant minerals in the crust are the two feldspars (orthoclase and plagioclase), quartz, olivine, and augite
---These five minerals are silicates, built from interlocking silicon and oxygen atoms

Mineral hardness

A method one could use to determine the hardness of unknown mineral samples would be:

-Scratch test: Test the item against materials of known hardness; for example, use your fingernail or the graphite in a pencil to attempt to scratch the items. This process should result in assigning a relative hardness to the unknown items.
-Mohs' scale of hardness: This scale assigns a fixed number to 10 reference materials. Talc (1) is the softest and diamond (10) is the hardest
-Cleavage: breaking along flat surfaces
-Density: how much matter is in the object

Mineral color

Affected by factors such as weathering and impurities

Mountain

-A land form that stretches above the surrounding land in a limited area, with a peak
-Usually produced by the movement of lithospheric plates
-The compressional forces, isostatic uplift, and intrusion of igneous matter forces surface rock upward, creating a land form higher than the surrounding features
-The height of the feature makes it either a hill or, if higher and steeper, a mountain
---A mountain is generally steeper than a hill, but there is no universally accepted standard definition for the height of a mountain or a hill, although a mountain usually has an identifiable summit
-The major mountains tend to occur in long linear arcs, indicating tectonic plate boundaries and activity
-Two types of mountains are formed, depending on how the rock reacts to the tectonic forces: block mountains or fold mountains
-Some isolated mountains were produced by volcanoes, including many apparently small islands that reach a great height above the ocean floor

River

-A natural flow of water, usually freshwater, traveling toward an ocean, a lake, or another stream
-In some cases, a river flows into the ground or dries up completely before reaching another body of water
-Usually larger streams are called rivers, while smaller streams are called creeks, brooks, rivulets, rills, and many other terms
-A component of the water cycle

Deserts

-Take up about 1/3 of the earth's land surface
-Usually have a large diurnal (day) and seasonal temperature range, with high daytime temperatures, and low nighttime temperatures (due to extremely low humidity)
-The temperature in the daytime can reach 45°C/113° or higher in the summer, and dip to 0°C/32° or lower in the winter
-Water acts to trap infrared radiation from both the sun and the ground, and dry desert air is incapable of blocking sunlight during the day or trapping heat during the night
-Thus, during daylight, most of the sun's heat reaches the ground and as soon as the sun sets, the desert cools quickly by radiating its heat into space
-Many deserts are formed by rain shadows

Rain shadow

Mountains blocking the path of precipitation to the desert

Weathering

The process of chemical or physical breakdown of earth rocks, soils, and their minerals

Mechanical/physical weathering

The breakdown of rocks, soils and minerals through direct contact with atmospheric conditions such as heat, water, ice, and pressure

Chemical weathering

The breakdown of rocks, soils and minerals through atmospheric chemicals or biologically produced chemicals (also known as biological weathering)

Soil

-The materials left over after the rock breaks down combine with organic material to create soil
-The mineral content of the soil is determined by the parent material; thus, a soil derived from a single rock type can often be deficient in one or more minerals for good fertility, while a soil weathered from a mix of rock types often makes more fertile soil

Erosion

The movement (carrying away or displacement) of solids (sediment, soil, rock, and other particles), usually by the agents of currents such as wind, water, or ice by downward or down-slope movement in response to gravity

Erosion and land use

-Erosion in many places is increased by human land use
-Poor land-use practices include deforestation, overgrazing, unmanaged construction activity, and road building
-Land that is used for the production of agricultural crops generally experiences a significantly greater rate of erosion than that of land under natural vegetation
-This is particularly true if tillage is used, which reduces vegetation cover on the surface of the soil and disturbs both soil structure and plant roots that would otherwise hold the soil in place
-Improved land-use practices can limit erosion by using techniques such as terrace building, conservation tillage practices, and tree planting
-A certain amount of erosion is natural and healthy for the ecosystem, but excessive erosion can cause damage by excessive loss of soil

Strata

-The layers of sediment deposited in a quiet environment
-Common sites of deposition are lakes, deltas at the mouths of rivers, beaches and sandbars along the coast, and (most important) the marine environment
-Commonly very extensive laterally and relatively thin vertically, like a blanket
-Law of original horizontality: most sediments were deposited in beds that were originally horizontal, and any tilting is due to later earth movements
-Law of superposition: younger beds were originally deposited above older beds

Fossils

-Traces of ancient life preserved in the strata as shells, footprints, and the like
-Soft plant and animal tissues decompose quickly in the presence of decay bacteria, which exist wherever oxygen exists
-Therefore, softtissue would most likely avoid decomposition and survive as a fossil in the most oxygen-free environment, such as lake-bottom mud
-Because life has evolved (changed) continually through geological history, the fossils in older strata differ from those found in more recent deposits

Example: The earliest fossil-rich beds have many trilobites, early crab-like creatures that have been extinct for hundreds of millions of years; discovery of fossil trilobites in a formation permits assignment of that bed to an early period

The geological time scale

-Used to arrange strata in a standard order
-Used to measure the amount of radioactive decay in minerals and calculate the time at which the rock formed
-The earth is believed to be about 5.6 billion years old
-The fossiliferous strata record is only the last 11% of the earth's history
-Human civilization has lasted only 10,000 years
-The immensity of geological time is the major discovery of geology
-There has been ample time for very slow processes to produce large consequences

The earth's structure

Has been inferred from its astronomical properties and seismic records of earthquake waves that have traveled through the interior of the earth

-Center: 3000°C (temperature rises from the surface to the center)
-Core: 31% of the earth's mass; iron and nickel metals, melted by the extremely high temperature of the center of the earth
-Mantle: Largest zone of the planet (68%); crystalline silicates, rich in magnesium, calcium, and iron; very hot and mainly solid, but local melting to magma is the source of volcanic eruptions
-Crust: Less than 1% of the earth; this relatively thin zone (5 to 25 miles) contains the only rocks we can study, even in the deepest mines or drill holes

Crustal rocks

Earth movements

-The result of forces within the earth, where temperature and pressure differences lead to instability
-The stress is particularly severe in orogenic zones, which are characterized by volcanism, metamorphism, deformation, and uplift
---Two styles of rock deformation are faulting and folding
---Edge-of-continent deformation is attributed to plate tectonics

Plate tectonics

-Large-scale movements of the earth's lithosphere
-The theory encompasses the older concepts of continental drift (first half of 20th century) and seafloor spreading (1960s)
-The outermost part of the earth's interior is made up of two layers: the lithosphere and the asthenosphere
-Lithosphere is comprised of the crust and the rigid uppermost part of the mantle
-Lithosphere is broken up into tectonic plates (7 major and many minor)
-The lithospheric plates ride on the asthenosphere
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-Giant masses of solid rock that float upon the earth's mantle
-These plates move in relation to one another at one of three types of plate boundaries: convergent/collision boundaries, divergent/spreading boundaries, and transform boundaries
-Earthquakes, volcanic activity, mountain-building, and oceanic trench formation occur along plate boundaries
-The intensity of the earthquake depends on the type of tectonic motion that caused the initial earthquake
-The lateral movement of the plates is typically at speeds of 50-100 mm annually

Continental drift

-Theory that the earth's continents were originally united as a supercontinent, Pangaea
-Established by Alfred Wegener in the early 1900s

Examples to support Wegener's theory:
-Paleontology: Fossil evidence indicates the similarity of fossils on both sides of the Atlantic Ocean
-Continental "jigsaw puzzle": The outlines of the continents seem to fit together—for example, the eastern coast of South America and the western coast of Africa
-Paleoclimatology (study of ancient climates): Ancient coral reefs (associated with warm water) are found in areas that could not currently support such growth
-Sea-floor spreading:
---The discovery of tectonic plate movement and sea-floor spreading provided proof for Wegner's theory
---The oceanic floor is not stationary
---The plates move because of incredible amounts of released energy
---During sea-floor spreading, new oceanic crust forms
---The Mid-Atlantic Ridge is an example
---In response to ocean-floor movement, the ocean floor expands in opposite directions
---Continents spread apart and away from the Mid-Atlantic Ridge

Divergent plate movements

-Occur when two plates pull away from each other
-Such faults are generally weak and shallow

Example: the Mid-Atlantic Range in the Atlantic Ocean

Convergent plate movements

-Occur when two plates push together
-Such faults are strong and relatively deep
-Where the strongest earthquakes occur

Example: mountain building in the Himalayas and the Andes

Transform plate movements

-Occur when two plates slip past each other
-Such faults are generally moderate and are relatively shallow

Example: The San Andreas Fault

Pacific Ring of Fire

-An area of frequent earthquakes and volcanic eruptions associated with the plate boundaries surrounding the Pacific Ocean
-In a 40,000 km horseshoe shape, it is associated with a nearly continuous series of oceanic trenches, volcanic arcs, and volcanic belts and/or plate movements
-Accounts for the majority of earthquakes and volcanoes worldwide
-Has 452 volcanoes and is home to over 75% of the world's active and dormant volcanoes
-90% of the world's earthquakes and 80% of the world's largest earthquakes occur along the Ring of Fire
-The Ring of Fire is a direct result and consequent of plate tectonics and the movement and collisions of crustal plates

Volcano

-An opening, or rupture, in a planet's surface or crust, which allows hot molten rock, ash, and gases to escape from below the surface
-Volcanic activity involving the extrusion of rock tends to form mountains or features like mountains over a period of time
-Volcanoes are generally found where tectonic plates are diverging or converging
-A mid-oceanic ridge, such as the Mid-Atlantic Ridge, has examples of volcanoes caused by divergent tectonic plates pulling apart
-The Pacific Ring of Fire has examples of volcanoes caused by convergent tectonic plates coming together
-By contrast, volcanoes are not usually created where two tectonic plates slide past one another
-Volcanoes can also form where there is stretching and thinning of the earth's crust
-Can be caused by "mantle plumes"; these so-called hotspots, as in Hawaii, can occur far from plate boundaries
-Hotspot volcanoes are also found elsewhere in the Solar System, especially on rocky planets and moons
-Volcanoes are also found in subduction zones, where the denser oceanic plates are forced under continental plates; this adds massive volumes of water to the mantle, allowing magma to melt more readily and rise to the surface to form volcanoes

Cataclysmic volcanic eruptions

-Can influence climate by sending tremendous volumes of dust, ash, and smoke into the atmosphere
-The resulting dust layer would act as a shield, blocking out much of the sun's rays
-This would result in lower global temperatures and a general cooling of the earth
-Scientists theorize that massive volcanic eruptions on a global scale contributed to the earth's cooling, resulting in the onset of the Ice Age

Petroleum exploration

-A continuous drill would find gas, oil, and water in that order
-The three substances occur in their order of density, with the lightest substance on top and the heaviest on the bottom
-Gas is lighter than the two liquids, and so it is on the top
-Oil floats on water, and so it is second
-On the bottom is the most dense substance, water

Meteorology

-The science of the atmosphere and weather

The composition of air

Air mass

-Characterized by similar temperatures and moisture levels
-On maps, the characteristics of an air mass are represented by two letters
-The lowercase letter represents moisture, and the uppercase letter represents temperature
-Maritime air forms over water and is associated with wet air
-Continental air forms over land and is associated with dry air
-Polar air forms south of the Arctic and is cold
-Tropical air forms over the Tropics and is warm
-mT = maritime tropical (wet, warm air)
-mP = maritime polar (wet, cold air)
-cT = continental tropical (dry, warm air)
-cP = continental polar (dry, cold air)

Hydrologic cycle

-Sun heats water in the oceans
-Water evaporates as vapor into the air
-Ice and snow can sublimate directly into water vapor
-Evapotranspiration: water transpired from plants and evaporated from the soil
-Rising air currents take the vapor up into the atmopshere where cooler temperatures cause it to condense into clouds
-Air currents move clouds around the globe and cloud particles collide, grow, and fall out of the sky as precipitation
-Some precipitation falls as snow and can accumulate as ice caps and glaciers, which can store water for thousands of years
-Snow packs can thaw and melt, and the ensuing water flows overland as snowmelt
-Most precipitation falls back into the oceans or onto land, where the precipitation flows over the ground as surface runoff
-A portion of runoff enters rivers, with stream flow moving water towards the oceans
-Runoff and groundwater are stored as freshwater in lakes
-Not all runoff flows into rivers; much of it infiltrates into the ground through percolation
-Some water infiltrates deep into the ground and replenishes aquifers, which store huge amounts of freshwater for long periods of time
-Some infiltration stays close to the land surface and can seep back into surface-water bodies (and the ocean) as groundwater discharge
-Some groundwater finds openings in the land surface and emerges as freshwater springs
-Over time, the water reenters the ocean, where the water cycle started

Hydrologic cycle (pic)

Hydrologic concepts

-Precipitation
-Canopy interception
-Snowmelt
-Runoff
-Percolation
-Subsurface flow
-Evaporation
-Sublimation
-Condensation

Precipitation

-Condensed water vapor that falls to the earth's surface
-Most precipitation occurs as rain, but also includes snow, hail, fog drip, graupel, and sleet

Canopy interception

The precipitation that is intercepted by plant foliage and eventually evaporates back to the atmosphere rather than falling to the ground

Snowmelt

The runoff produced by melting snow

Runoff

-The variety of ways by which water moves across the land
-This includes both surface runoff and channel runoff
-As it flows, the water may percolate into the ground, evaporate into the air, become stored in lakes or reservoirs, or be extracted for agricultural or other human uses

Percolation

The movement of rainwater as it filters through soil and rocks into the ground, becoming groundwater

Subsurface flow

-The flow of water underground, in the vadose zone and aquifers
-Subsurface water may return to the surface (as a spring or by being pumped) or eventually seep into the oceans
-Water returns to the land surface at lower elevation than where it entered, under the force of gravity or gravity-induced pressures
-Groundwater tends to move slowly and is replenished slowly, and so it can remain in aquifers for thousands of years

Evaporation

-The transformation of water from liquid to gas phases as it moves from the ground or bodies of water into the overlying atmosphere
-The source of energy for evaporation is primarily through solar radiation
-Evaporation often implicitly includes transpiration from plants, although together they are specifically referred to as evapotranspiration

Sublimation

The state change where a solid (ice or snow) changes directly to a gas (water vapor)

Condensation

The transformation of water vapor to liquid water droplets in the air, producing clouds and fog

Weather phenomena on earth

-Common: wind, clouds, rain, snow, fog, dust storms
-Less common: natural disasters such as tornadoes, hurricanes, and ice storms
-Almost all familiar weather phenomena occur in the troposhere (the lower part of the atmosphere)
-Weather does occur in the stratosphere and can affect weather lower down in the troposhere

Types of clouds

-Cirrus
-Stratus
-Cumulonimbus
-Altostratus

Cirrus clouds

Featherlike clouds that indicate fair weather

Stratus clouds

Smooth layers of low clouds that indicate a chance of drizzle or snow

Cumulonibus clouds

Large, dark clouds that indicate thunderstorms

Altostratus clouds

Piled in waves and indicate rain or snow

Why weather occurs

-Weather occurs primarily due to density (temperature and moisture) differences between one location and another
-These differences can occur due to the angle of the sun at any particular spot, which varies by latitude from the tropics
-The farther from the tropics you are positioned, the lower the angle of the sun
-This causes those locations to be cooler due to the indirect sunlight
-The strong temperature contrast between polar and tropical air gives rise to the jet stream

Surface temperature differences

-Cause pressure differences
-A hot surface heats the air above it and the air expands, lowering the air pressure and its density
-The resulting horizontal pressure gradient accelerates the air from high to low pressure, creating wind, and the earth's rotation then causes the curvature of the flow through the Coriolis effect
-The atmosphere is a chaotic system, and so small changes to one part of the system can grow to have large effects on the system as a whole
-This makes it difficult to accurately predict weather more than a few days in advance

Sun and oceans' affect on weather

-The sun and oceans can also affect the weather of land
-If the sun heats ocean waters for a period of time, water can evaporate
-Once evaporated into the air, the moisture can spread over nearby land, thus making it cooler

Differential heating

-The motive force behind land breezes and sea/lake breezes, also known as on- or off-shore winds
-Land absorbs and radiates heat faster than water, but water releases heat over a longer period of time
-The result is that, in locations where sea and land meet, heat absorbed over the day will be radiated more quickly by the land at night, cooling the air
-Over the sea, heat is still being released into the air at night, and rises
-This convective motion draws the cool land air in to replace the rising air, resulting in a land breeze in the late night and early morning
-During the day, the roles are reversed
-Warm air over the land rises, pulling cool air in from the sea to replace it, giving a sea breeze during the afternoon and evening

Mountain breezes and valley breezes

-Due to a combination of differential heating and geometry
-When the sun rises, it is the tops of the mountain peaks which receive first light, and as the day progresses, the mountain slopes take on a greater heat load than the valleys
-This results in a temperature inequality between the two, and as warm air rises off the slopes, cool air moves up out of the valleys to replace it
-This upslope wind is called a valley breeze
-The opposite effect takes place in the afternoon, as the valley radiates heat
-The peaks, long since cooled, transport air into the valley in a process that is partly gravitational and partly convective and is called a mountain breeze

El Niño and La Niña

-Officially defined as sustained sea surface temperature anomalies of magnitude greater than 0.5°C across the central tropical Pacific Ocean
-El Niño is characterized by unusually warm ocean temperatures in the eastern equatorial Pacific
---El Niño's warm current of nutrient-poor tropical water, heated by its eastward passage in the Equatorial Current, replaces the cold, nutrient-rich surface water of the Humboldt Current, also known as the Peru Current, which supports great populations of fish
-La Niña is characterized by unusually warm ocean temperatures in the same area
---Atlanta tropical cyclone activity is generally enhanced during La Niña
-The La Niña condition often follows the El Niño, especially when the latter is strong

Climate

-Refers to the long-term weather patterns of a large geographical area and takes into account temperature, humidity, and precipitation
-Latitude is the best determiner of climate, as it is consistently and directly correlated with temperature
-The equator, at zero degrees latitude, generally has a tropical climate (warm and wet); at the extreme northern and southern latitudes (polar regions), the climate is very cold and dry
-Rain shadows, as well as water currents, elevation and so forth, affect climate, but latitude is the primary factor

Estuary

-A semi-closed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea
-Often associated with high levels of biological diversity
-Typically the tidal mouths of rivers and are often characterized by sedimentation or silt carried in from terrestrial runoff, frequently from offshore
-They are made up of brackish water
-Often given names like bay, sound, fjord, etc.; the terms are not mutually exclusive
-Ecosystems that are under threat from human activities such as pollution and overfishing

World/global ocean

-Comprises one global, interconnected body of salt water often (though generally recognized as several separate oceans)
-A continuous body of water with relatively free interchange among its parts
-Major oceanic divisions are defined in part by the continents, various archipelagos, and other criteria: these divisions are (in descending order of size) the Pacific Ocean, the Atlantic Ocean, the Indian Ocean, the Southern Ocean and the Arctic Ocean
-Smaller regions of the oceans are called seas, gulfs, bays, and other names
-Oceans cover 3/4 of the earth's surface
-The evaporation of these oceans is how we get most of our rainfall, and their temperature determines our climate and wind patterns
-Life within the ocean had already evolved 3 billion years prior to the movement of animal and plant life on land

Surface ocean currents

-Classified as warm-water or cold-water currents
-Surface ocean temperature is a major determiner of coastal climate
-The Gulf-Stream is a warm-water current that carries warm water from the Tropics to the Arctic regions of the North Atlantic Ocean
-This accounts for higher temperatures and higher humidity on the Eastern Seaboard during the summer
-The cold-water current that flows north to south off the California coast keeps the West Coast fairly cool during the summer
-Cold-water currents create cooler temperatures in areas that would otherwise be much warmer

Tides

-The rising of the earth's ocean surface caused by the tidal forces of the moon and the sun acting on the oceans
-Cause changes in the depth of the marine and estuarine water bodies and produce oscillating currents known as tidal streams, making prediction of tides important for coastal navigation
-The changing tide produced at a given location is the result of the changing positions of the moon and sun relative to the earth, coupled with the effects of the earth's rotation and the bathymetry of oceans, seas, and estuaries
-Sea level measured by coastal tide gauges may also be strongly affected by wind
-Tides may be semidiurnal or diurnal
-The tidal force produced by the sun is 46% as large as that produced by the moon
-The gravitational attraction between the moon and the earth (and to a lesser degree, the sun) causes the tides
-The gravitational attraction of the moon causes the oceans to bulge out on the sides of the earth facing the moon
-Another bulge also occurs on the opposite side of the earth as the earth is being pulled toward the moon
-Due to the rotation of the earth, two tides occur each day

Semidiurnal

-Two high waters and two low waters each day
-In most locations, tides are semidiurnal

Diurnal

One tidal cycle per day

Spring tide

-Around a new or full moon, when the sun, moon, and the earth form a line, the tidal forces due to the sun reinforce those of the moon
-The tide's range is at a maximum and is called a spring tide (spring as in "to jump/leap," not the season)

Neap tide/neaps

-When the moon is at first quarter or third quarter, the sun, earth and moon form a 90-degree (right) angle with the earth at the vertex
-The combined effect of this alignment of the sun, earth, and moon results in tidal ranges on the earth
-When a neap tide occurs, the gravitational forces on the earth from both the sun and moon are minimized
-Tidal range is lowest during neap tide

Tidal range

The difference between levels of ocean water at high and low tides

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