Intro to Earth Science - Exam 3

Describe what the atmosphere is, including the different components found in the atmosphere. List the two most abundant gases in the atmosphere.

Atmosphere is layer of gases that surround a planet.


Two most abundant gases = Nitrogen and Oxygen

Other components = Argon, Carbon Dioxide, and Water Vapor

Describe/explain how and why atmospheric pressure changes vertically through the atmosphere.

The lower you go, the higher the atmospheric pressure is because there are more air particles above you

Describe the temperature changes that occur vertically through the troposphere and stratosphere.

Troposphere = the higher you go, the colder it gets

Stratosphere = the higher you go, the hotter it gets

Describe four ways that matter interacts with visible light and other electromagnetic radiation.

Transmission - moves through without transferring energy to object/gas

Absorbed - some/all energy may be converted to heat

Reflected - waves bounce back organized way

Scattered - waves bounce back in variable direction

Summarize the electromagnetic spectrum, indicating the relative order of different types and wavelengths of electromagnetic radiation (EMR) on the spectrum.

1. Electromagnetic spectrum shows different waves that make up the whole spectrum of electromagnetic radiation.

   1. Left side = highest energy and frequency, shorter wavelength

   2. Right side = lowest energy and frequency, longer wavelength

   3. Visible light: ROY G BIV,

      1. Red is longest wavelength (least energetic)

      2. Violet is shortest wavelength (most energetic)

   4. Correct order from left to right:

      1. Gamma Rays, X rays, Ultraviolet, Visible light, Infrared, Microwaves, Television/FM Radio, Short wave radio, Standard AM radio, Long radio waves

Describe how temperature controls the range of electromagnetic radiation (EMR) wavelengths a body emits. Compare types and wavelengths emitted by the Earth and Sun.

The hotter the body, the shorter the wavelength
Earth = very cool, longer wavelength, 10 microns
Sun = very hot, bw green n yellow portion on spectrum, 0.5 microns

Explain the effects of scattering of visible light on optical effects such as sky color and darkness of shadows.

Scattering visible light, especially Rayleigh scattering, explains the blue color of the sky, since shorter (blue) wavelengths are scattered more strongly than longer ones.

Shadow darkness: Shadows are not fully dark because scattered sky light fills them; their brightness depends on how much scattered light is available.

Explain what Ozone is, how it forms, and where it is in our atmosphere.

Ozone is what protects the Earth from the Sun’s harmful UV rays located in the stratosphere
How its formed: Incoming UV radiation splits O2 into two separate atoms. Each oxygen atom collides with another O2, making Ozone (O3)

Explain why depletion of Ozone concentrations harms us and describe how human activity can deplete Ozone levels.

1. If we deplete, the high energy UV radiation which Ozone protects us from would reach the Earth’s surface.

2. Ozone is destroyed by CFCs (chloro-flourocarbons) such as coolants for ACs, refrigerators, and aerosol sprays

Describe the basic goals and reason for the Montreal Protocol of 1987 and its result on Ozone levels and the size of the Ozone hole.

1. Montreal Protocol of 1987 - eliminated the production and use of CFCs

2. Ozone level is slowly recovering 

3. Ozone hole is slowly closing

Explain the difference between rotation of the Earth and orbital motion.

Earth's rotation - spins once every 24 hours around its axis at the poles

Orbital motion - revolve around the Sun once a year (slightly elliptical)

Explain the two ways the angle of the Sun’s rays affects the distribution/intensity of heat at the Earth’s surface.

1. 1) Intensity/Concentration of energy

2. 2) Amount of atmosphere the radiation passes through

Describe how the tilt axis of the earth controls the seasons we experience on Earth.

1. The tilt changes how directly sunlight hits different parts of Earth, when the Northern Hemisphere is tilted toward the Sun, sunlight strikes it more directly.

2. The tilt causes changes in day length, the hemisphere tilted toward the Sun gets longer days and shorter nights.

   1. Earth’s rotation axis is 23.5 degrees from perpendicular to plane of the ecliptic

Explain how the solstices and equinoxes are defined by day length and how this relates to the position of the Earth’s tilt axis.

1. During equinoxes, Earth’s tilt is sideways relative to the Sun, so both hemispheres receive equal sunlight and day and night are nearly the same length.

2. During solstices, the tilt points either toward or away from the Sun, creating the longest and shortest days of the year depending on the hemisphere.
   

3. In short, equinoxes occur when neither hemisphere is tilted toward the Sun, while solstices occur when the tilt is at its maximum toward or away from it.

Explain how the Tropics of Cancer and Capricorn are defined, identify their locations, and how these relate to the Earth’s tilt axis.

1. Definition

   1. The Tropic of Cancer (north) - 23.5° North latitude

      1. Northernmost latitude where the Sun can be directly overhead at noon. Sun is directly overhead here during the June solstice, when the Northern Hemisphere is tilted toward the Sun.

   2. Tropic of Capricorn (south) -  23.5° South latitude

      1. Southernmost latitude where the Sun can be directly overhead at noon. Sun is directly overhead here during the December solstice, when the Southern Hemisphere is tilted toward the Sun.

2. Relation to Earth’s Tilt

   1. Earth’s axis is titled 23.5° relative to its orbit around the Sun. Because of the tilt, the Sun’s most direct rays can shift 23.5° north or south. Those make the Tropic of Cancer and Capricorn

The tropics exist because Earth’s tilt determines how far north or south the Sun can be directly overhead.

Explain how the Arctic and Antarctic Circles are defined, identify their locations, and how these relate to the Earth’s tilt axis.

1. The Arctic and Antarctic Circles are special latitudes where locations experience at least one full day each year of 24-hour daylight or 24-hour darkness.
   
   

2. The Arctic Circle lies at 66.5° N, and the Antarctic Circle lies at 66.5° S.

3. These locations are set by the fact that they sit 23.5° from the poles—the same angle as Earth’s axial tilt.

2. Relation to Earth’s tilt axis

Because Earth’s tilt causes the poles to lean toward or away from the Sun during solstices, areas above or below these circles experience phenomena like the Midnight Sun (24-hour daylight) and Polar Night (24-hour darkness).

Explain how the lengths of days/nights vary with latitude and how they change over the course of a year.

1. Day and night lengths vary with latitude because different parts of Earth receive different amounts of sunlight throughout the year. 

2. Near the equator, days are ~12 hours year-round, while at higher latitudes, day length changes dramatically, with poles experiencing 24 hours of daylight/darkness seasonally, peaking in summer (longer days) and minimizing in winter (shorter days/nights)

Describe approximately how much of the Sun’s energy reaches and is absorbed by the Earth’s surface and comment on processes that prevent the rest from reaching the surface. Explain albedo and what controls the albedo.

1. 50% of Sun’s energy reaches and is absorbed by Earth’s surface

   1. 30% reflected back into space

   2. 20% absorbed by clouds and atmospheric gases

2. Processes that prevent the rest from reaching the surface

   1. Reflection by clouds, atmosphere, bright surfaces, scattering sunlight or absorption by the atmosphere

3. Albedo = fraction of total radiation that is reflected by a surface

Varies by material, color, and sun angle

Explain what the greenhouse effect means and how greenhouse gases contribute to the heating of planetary atmospheres.

1. Greenhouse effect = process by which a planet’s atmosphere traps heat and keeps the surface warmer than it would be without the atmosphere

2. Greenhouse gases contribute to heating because CO2 will trap the long wave radiation from the Earth.

What are the two main greenhouse gases in the atmosphere that, in part, result from human activities?

Carbon Dioxide and Methane (CO2) and (CH4)

Explain how and why summer and winter temperatures differ between coastal regions and interior locations (inland locations away from the oceans).

the ocean has high specific heat which means it takes longer for it to heat up. the land has low specific heat.

so near the coast, the summer is cooler and winter is warmer

inland, summers are much hotter and winter is much colder

Explain the effect of clouds on night-time temperatures.

1. Clouds absorb and re-emit heat radiated from Earth at night, which reduces heat loss and leads to less cooling.

Explain the process of convection in the atmosphere and the significance of latent heat in terms of warming/cooling during the formation of convective clouds.

1. Process of Convection (mechanism of heat transfer)

   1. Sun beats down through the morning

   2. Heats up the air near ground surface

   3. When air heats up, it expands and is less dense

   4. When it's less dense, it will rise through cooler air

   5. As it rises, we get condensation and condensation makes latent heat.

   6. Results in cloud formation

Significance of latent heat = Condensation releases latent heat, which warms the surrounding air and further uplifts. This added heat is an important factor in the formation of hurricanes.

Define what isobars represent on a weather map and their relationship to wind (direction & speed) and weather.

1. What are Isobars 

   1. Isobars are lines on maps that connect areas of equal air pressure. Wind blows from high pressure to low pressure but Coriolis effects cause deflection.

2. Relationship to wind, direction, speed, and weather

   1. Direction = wind moves from high pressure to low pressure

   2. Closer isobars = stronger winds

High pressure areas = good weather

Identify the isobar patterns for high-pressure and low-pressure systems (such as hurricanes).

1. Identify the isobar patterns for high-pressure and low-pressure systems (such as hurricanes).

   1. High pressure = Isobars form a circular pattern with the highest pressure in the center. They are widely spaced, indicating a weak pressure gradient and lighter winds. High-pressure systems are typically associated with calm, clear weather.

   2. Low pressure = Isobars form a bullseye or spiral pattern around the center. They are tightly packed, indicating a steep pressure gradient and strong winds. Air spirals inward toward the low-pressure center.

Explain how the Coriolis effect affects wind directions, particularly in hurricanes.

The Coriolis effect, made by Earth’s rotation, deflects air to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. In hurricanes in the Northern Hemisphere, this deflection causes winds to circulate counterclockwise.

Describe where hurricanes do and do not form and when they form.

1. Form = In warm tropical and subtropical waters between 5° and 25° latitude. Water temperature is usually 27°C or 80°F.

2. Do not form = Within 5° of the equator because the Coriolis effect is too weak.

When they form = Late summer to early fall even though the summer solstice is in June, due to the lag in ocean heating.

Describe the characteristics of the eye, eyewall, and outer bands of hurricanes.

1. Eye: The center of the hurricane, calm. Skies may clear temporarily if the eye passes over a location.

2. Eyewall: Surrounding the eye, highest wind speeds and heaviest rainfall The steepest pressure gradient occurs here.

Outer bands: Spiraling bands around the hurricane, intermittent rainfall and gusty winds.

Describe/explain the processes that lead to hurricane formation and the necessary “ingredients” for hurricane formation.

1. Hurricane formation = tropical disturbances, which are disorganized areas of clouds and thunderstorms with little rotation.

2. Necessary ingredients: warm, moist air from the ocean surface, which rises and condenses into clouds, releasing latent heat.

   1. As air rises, surface pressure drops, making a low-pressure center. Winds flow inward toward this low, and Coriolis effect causes rotation.

   2. This cycle continues, bringing more warm, moist air into the system, sustaining and intensifying the storm.

Describe the processes that lead to the decay of hurricanes.

1. Moving over colder ocean waters = reduces the supply of warm, moist air, weakening the storm.

2. Moving onto land = prevents the hurricane from drawing moisture from the ocean, and friction slows winds.

3. Unfavorable upper-level winds = can disrupt the outflow and diminish storm intensity.

Hurricanes die when these conditions prevent continued convective uplift and moisture inflow.

Define storm surge and the processes that cause it. From a hurricane map, determine the locations of greatest and least storm surges.

1. Storm surge = dome of water that rises above normal tide levels during a hurricane

2. Caused by:

   1.  Winds blowing toward shore, piling water up

   2. The hurricane itself pushing water inland

3. Greatest storm surge: Occurs on the side of the hurricane where wind is blowing toward the shore.

Least storm surge: Occurs on the side where wind is blowing away from the shore.

Identify the parts of hurricanes and other factors that control the greatest areas of wind damage and flooding.

1. parts = eye, eyewall, outerbands

2. wind damage = eye wall

Flooding = rainbands and storm surges

Describe the differences between climate and weather.

1. Weather = conditions at a location at that particular time (what you get)

   1. Assessed by things like temperature, humidity, and wind

2. Climate = changes in weather over time (what you expect to get)

   1. Assessed by things like seasonal variations in temperature and precipitation

Describe the main atmospheric factors that are used to define different climate zones.

Temperature and precipitation

Briefly describe the methodologies scientists use to identify past glaciations, determine past global temperatures (ocean and atmospheric), and determine past CO2 levels.

1. To find past glaciations = glacial landforms, striations, glacial deposits (diamictites and dropstones)

2. To find past temperatures = oxygen isotopes from deep sea sediments and from ice cores

To find past CO2 levels = CO2 from ice cores

Describe the time period referred to as “snowball Earth” and evidence for this event.

1. Snowball Earth was 720 to 635 million years ago when Earth was nearly completely covered in ice, including ocean surfaces.

Evidence is diamictites interlayered with limestones and Paleomagnetic evidence that ice sheets formed at low latitudes

Describe the three different Earth-Sun relationships that define Milankovitch cycles. Identify the general timescales on which they operate. Explain how these affect global climate and how they correlate with glacial-interglacial cycles during the past ~two million years (the last “ice ages”)

1. Eccentricity = shape of earth’s orbit around the sun, changes from circular to elliptical. Cycles that span about 100,000 years. 

2. Obliquity = the angle Earth’s rotation axis makes with the orbital plane. The cycle spans 41,00 years.

3. Precession = wobbling of Earth’s axis. The cycle spans about 26,000 years.

Effect of Milankovitch is the change in distribution of energy around the globe which changes the length of seasons and days

Explain what feedback mechanisms mean (both positive and negative) and give examples. Explain how CO2 does or does not correlate with past glacial/interglacial cycles and whether changes in CO2 are a primary driver or feedback for these cycles.

1. Positive feedback amplifies the initial change

   1. Cooling leads to more ice leads to more albedo leads to more cooling

2. Negative feedback counteracts the initial change

   1. Warming → oceans absorb more CO₂ → less CO₂ in the atmosphere → weaker greenhouse effect → less warming

3. There is a correlation between CO2 and past glacial cycles. 

Changes in CO2 are more of an effect instead of being a driver for these cycles

Identify when the last glacial period ended and define the approximate global temperature change since that time.

1. The last glacial period ended about 18,000 years ago

Approximate global temperature change was an increase of 10° celsius

Define the “Medieval warm period” and “Little ice age”.

1. Medieval warm period = 950 to 1250 AD

   1. Caused by solar radiation, decrease in volcanic activity and changes in ocean currents

2. Little ice age = 1400s to 1800s

   1. Global temps dropped, waterways in northern Europe froze

Caused by = volcanic activity, changes in ocean circulation, lower solar activity.

How many degrees C & F have average global temperatures increased since ~1880? Describe the nature of this change (i.e., was this a continuous warming, or were there periods of no warming (or cooling) during this time).

1. Avg global temps increased >1° C and 2.2° F

2. Nature of this change = not continuous increase, slight cooling from 1941 to 1976

3. Rise is large and rapid

Describe the changes in atmospheric CO2 levels since ~1880. Compare present CO2 levels with past interglacial periods over several hundred thousand years. Compare the amount of CO2 released annually from the burning of fossil fuels with that released by volcanic activity.

1. Changes in atmospheric CO2 levels = dramatic increase bc of things like burning of fossil fuels, cement production, and land-use changes

2. Present CO2 levels are higher than during past interglacial periods.

CO2 released annually from the burning of fossil fuels is much greater than that from volcanic activity.

Describe how volcanic eruptions can lead to cooling (in addition to warming from CO2).

By releasing ash and sulfur dioxide into the stratosphere, the ash blocks sunlight and sulfur dioxide combines with water vapor to make sulfuric acid aerosols, which scatter sunlight and reduce solar radiation reaching the Earth's surface.

Explain whether or not Milankovitch cycles and changes in Solar energy output can be responsible for warming over the past ~100 years. Explain why or why not.

1. No , Milankovitch and changes in Solar energy can not be responsible for warming bc Milankovitch is too slow and Solar energy has not made enough energy for it to contribute

Describe what the IPCC is/does and their conclusions regarding the causes of recent global warming.

1. IPCC is an organization whose premise is to provide the government with scientific info to make climate policies.

IPCC’s causes for recent global warming = human activities, primarily through the emission of greenhouse gases like CO₂, are the primary cause of recent global warming.

Describe the factors that go into future climate models.

Greenhouse gas emissions, volcanic activity, solar radiation

Describe some possible consequences of continued global warming.

1. Hurricanes = more intense rainfall, more wind intensity, number of storms are constant or might decreases

2. Sea level rise = storm surges will have a greater effect, melting continental ice sheets, thermal expansion of ocean water

3. Drought and floods = both will become more severe and frequent

Describe the distribution of elevations found on Earth (as displayed by a hypsometric curve). Explain the reason for this distribution.

1. Earth’s hypsometric curve shows a bimodal distribution of elevations:

   1. ~29% of Earth’s surface is above sea level (continents), and ~71% is below sea level (ocean basins).

   2. A large portion of land lies between sea level and ~1–2 km above sea level.

   3. A very large portion of the seafloor lies between 3 km and 6 km below sea level, accounting for close to 50% of Earth’s surface.

2. Reason for bimodal distribution

   1. Earth has two different types of crust:

      1. Oceanic crust - thin (5–7 km), higher density → sits lower.

Continental crust- thick (35–45 km), low density → sits higher.

List the major components that make ocean water “salty” and the average salinity of the oceans.

1. Average salinity of seawater:

   1. 35 per thousand (35‰), equivalent to 3.5% dissolved material.

2. Major dissolved components:

   1. Chlorine = 55%

   2. Sodium = 30%

Explain the processes that affect the salinity of seawater.

1. Process that decrease salinity

   1. River runoff

   2. Rainfall

   3. Melting icebergs

2. Process that increase salinity

   1. Evaporation

   2. Formation of ice

Describe the relationships between carbon dioxide and the acidity of ocean waters. Explain how this affects marine organisms that make their shells from seawater.

1. ⅓ of carbon dioxide released by human activities dissolves into oceans where it reacts with seawater to make carbonic acid.

2. This lower pH of seawater makes it more acidic making it harder for marine organisms to build calcium carbonate shells.

Describe the thermocline and specifically how temperatures vary with depths in the oceans (in both low latitudes and the polar regions).

1. Thermocline is the layer within which temperature changes rapidly with depth.

   1. Temps varying in low latitudes

      1. Warm water in first few 100 meters

      2. 200-300m temp drops, gets colder

      3. Deep ocean temps stabilize at near freezing

   2. Temps varying in polar regions

      1. Little sun exposure makes surface water already cold

      2. Weak thermocline most of the year

      3. Temps usually cold from surface to depth

Explain how salinity and temperature affect the density of ocean water

Salinity increase = density increase

Temp increase = density decrease bc as water gets colder it contracts and gets denser.
Temp has more sway over density relative to salinity

Explain what drives surface ocean currents.

Wind. As the wind blows, it drags the upper layer of water

Define gyres as they pertain to ocean surface currents. Sketch and explain the main patterns of ocean currents in the Northern Hemisphere versus those in the Southern Hemisphere.

Gyres are large surface curtains formed by wind patterns, the Coriolis effect, and the shape of ocean basins.

Northern hemi = clockwise, deflect air to the right

Southern hemi = counterclockwise, deflect air to the left

Describe the Gulf Stream current and explain how the ocean currents affect the climate of northern Europe.

This current is a warm current coming from an equatorial region. They go from the Florida coast to the North Atlantic ocean. They carry warm water and heat from low latitude to high latitude.

Makes northern Europe more warm than other places near the same latitude because hot water and heat is blown towards there.

Explain the main factors that produce the Coriolis effect.

Earth rotation. The closer you get to the equator, the faster you move.

Other factors include Earths tilt

Explain the motion and driving forces of thermohaline circulation in the oceans.

1. At high latitudes, seawater becomes colder and saltier which increases its density. 

2. This dense water sinks and drives deep ocean circulation, known as thermohaline circulation, which is ultimately powered by differences in water density caused by temperature and salinity

Explain the causes (greater and lesser controls) of tides and describe the positions of the Earth-Moon-Sun when tides are highest and lowest. Explain the time between high/low tides and how the Earth and Moon control this.

1. Tides caused by gravitational pull of the Moon on oceans

2. Moon plays greater control

3. Sun plays a lesser control

   1. When the Sun is behind the Moon, the high tides get higher,  the low tides get lower

When the Sun is on a different side than the Moon, the forces cancel each other

List the factors that control the height, wavelength, and period of ocean waves.

1. Speed, duration, distance (fetch) of wind

   1. Increasing all factors will increase energy in waves, increase waves

Describe the motion of ocean waves, how motion changes with depth and as they approach the shore

1. Waves move from wind/storm areas and change to swells.

2. At shoreline waves are combination of swells from distant and local winds

Energy decreases as depth decreases

Explain what wave refraction means as it pertains to ocean waves approaching the shoreline.

1. Wave refraction is the bending of ocean waves as they approach the shoreline. 

It happens because part of a wave enters shallow water sooner than the rest, causing that part to slow down.

1. Describe the movement of sand grains as waves approach the shore obliquely.

Swash moves sand towards the beach

Backwash moves sand away from the beach

Describe the movement of rip currents, how they form, and what you should do if caught in one.

1. Rip currents are channelized flow of water moving away from shore

They form when backwash becomes concentrated in low spots on the ocean floor.
If caught, should swim parallel to the shore

Describe the differences between the inner/terrestrial planets (including Earth) and the outer/Jovian planets in size, composition, and density.

1. Inner/Terrestrial = Earthlike, smaller, denser

Outer/Jovian = Jupiterlike, larger, not that dense

The solar system began as a nebula. Describe the nebula in terms of shape and composition and the events that led to the formation of the proto-Sun.

1. Nebula is a cold cloud of interstellar gas and dust that was slowly rotating and moving through the galaxy

2. Formation

   1. A shock wave, from a nearby supernova, caused the cloud to collapse inwards. 

From the collapse, temperatures increased, turning everything into gas, and most of the gas collected in the center and made the protosun.

Explain why the spin rate of the solar nebula increased and the important effect this had on the shape of the nebula.

1. As the cloud collapsed, the conservation of angular momentum made its spin rate increase. 

The increased rotation caused the cloud to flatten into a disk shape.

Describe the temperature gradient in the accretion disk around the sun and explain how this gradient influenced the distribution of planet types (i.e., why are inner planets dominantly rocky material and the outer planets dominantly frozen gases & liquids and much larger?).

1. The accretion disk had a temperature gradient, with high temperatures near the protosun and cooler temperatures farther away. 

2. Near the Sun, only materials with high melting points—rocks and metals—could become solids, so the inner planets formed from rocks and metals. 

Farther out, temperatures were low enough for ices. Because the outer planets had solids made of rocks + metals + abundant ices, they grew much larger and were composed mainly of ices, liquids, and gases, producing the Jovian planets.

Describe how this material eventually formed planets after small solids began to condense in the disk around the sun.

1. As the disk cooled, gases condensed into solids. Tiny particles stuck together through electrostatic forces. Random collisions caused dust and other small particles to grow. 

They developed gravitational fields that attracted more material. These growing bodies kept colliding until they formed planets.

Describe where most of the mass in the solar system is found.

99.85% of the mass of the solar system is in the Sun

Identify the estimated age for the Earth and solar system formation and explain how scientists have determined this age.

1. 4.56 billion years

Determined this age from isotopic dating of meteorites, especially the Allende meteorite. Since no older material exists, this marks the start of the solar system forming

Identify the age of the oldest rocks and minerals found on Earth.

1. The oldest minerals on Earth are about 4.4 billion years old (zircons eroded from rocks that no longer exist). 

The oldestrocks are close to 4 billion years old.

Explain what is meant by the period of “late heavy bombardment” and how this may be used to estimate the ages of planetary surfaces.

If more cratered = older

Briefly describe the most popular theory for the formation of the moon.

Giant Impact = states the moon formed from the remains of the collision between the proto Earth and another Mars sized smaller body

Explain how planetary surfaces are dated.

1. Look at density of impact craters in given area

   1. More craters in area = older surface

 Explain the materials/features produced from meteorite impacts and the processes that form them.

1. High velocity impact >50 MPH = creates shockwaves

2. Products

   1. Ejecta comes out and covers area around crater

   2. Larger impacts have a central peak

Describe the lunar regolith and the general processes that form it

1. Lunar regolith = surface covered by blanket of debris varying in thickness

Process to make Lunar Regolith = continued bombardment of meteorite impacts

Explain how “daily” temperatures on the Moon vary and the two characteristics that lead to these extreme temperatures.

1. Since the moon has no atmosphere, the daily temperature varies

2. Two characteristics leading to extreme temps

   1. Having no atmosphere

Slow rotation 

Explain why we believe the Moon once had a magnetic field even though there is not one today.

When looking at old lunar samples, we see they formed in the presence of magnetic field