Earth Sci 1 S1 Notes

Branches of Earth Science:

  • Geology: Internal and external changes to the land on Earth (ex. volcanoes)

  • Meteorology: Study of the atmosphere (properties and composition, weather + climate)

  • Oceanography: Studies ocean/seas (seafloor, motions, water properties)

  • Astronomy: Study of space/objects outside of our atmosphere (ex. planets, stars, asteriods, etc)

Steps of the Scientific Method:

  1. State a problem

  2. Gather info

  3. Form a hypothesis

  4. Test your hypothesis

  5. Analyze results

  6. Form a theory or conclusion

Inference: An educated guess based on observations, ex. The tree fell down, so it must have been windy

Observation: Using your eyes or scientific instruments to get information. ex. The ant has two antennae

Prediction: A statement of something that you think is going to happen in the future. ex. There will be an earthquake in San Francisco in 2 years

Doppler Effect:

  • The change in wave frequency during the relative motion between a wave source and its observer

  • Example: When a police car with its siren on passes by, the frequency of its waves will increase and it will sound more high pitched

Red-Shifted Spectra: When light is stretched, so it appears a little more to the red side of the spectrum. In astronomy, it means something is moving away from us because the waves are being stretched out.

Types of Spectra:

  • Continuous, source: incandescent bulb, full rainbow

  • Bright line, source: element

  • Absorption, source: star, filtered light

How to determine the composition of a star using its spectra: When you get the spectrum of a star, there will be random black lines in the spectrum, and you have to find elements that match those black lines to determine the stars composition

Converting between units:

1 cm = 0.01 meters, 100 cm = 1 meter, 1000 meters = 1 km, 1 meter = 0.001 km

Electromagnetic Spectrum:

  • In order from longest to shortest wavelength:

    • Microwaves

    • Radio Waves

    • Infrared

    • Visible (Red, Orange, Yellow, Green, Blue, Indigo, Violet)

    • UV Rays

    • X-Rays

    • Gamma

  • In the atmosphere, Short infrared waves are absorbed in the thermosphere and UV rays are absorbed by the ozone layer, and Infrared and Visible light reaches the Earth’s surface.

Nebular Hypothesis:

  • Nebula (a cloud of dust and gas) spins, contracts, then flattens

  • Protosun is formed

  • Nuclear fusion creates the sun

  • Space Rocks collide to form planets

  • 4 planets that were closest to sun had their gasses heat up and the escape velocity of those gases allowed them to escape, making the 4 planets closer to the sun less gassy, creating the inner and outer planets

Relationships on a HR Diagram:

  • Color: Darker colors colder and dimmer

  • Temperature: Lighter colors (blue and white) are hotter than darker colors (red and orange)

  • Hottest to coldest: blue, white, yellow, orange, red

  • Brightness: Lighter colors are much brighter than darker colors

  • Lifespan: Cooler and dimmer stars live the longest (red stars)

Big Bang Theory:

  • All matter and energy was confined together in one hot, dense body

  • 14 billion years ago matter spreads out

  • Basic elements form

  • Clouds of Hydrogen and Helium form

  • Matter comes together by gravity, forming galaxies and stars

  • Nuclear reactions in stars create heavier elements

  • Universe is still expanding

    Evidence of the Big Bang:

    • Cosmic Background Radiation (Microwaves spread out evenly throughout space)

    • Red-shifted spectra

    • Hydrogen and Helium make up most of the atmosphere today

Age of Universe: 13.7 billion years old

Age of Solar System: 4.5 billion years old

Age of Earth: 4.5 billion years old

Inner vs. Outer Planets:

Inner:

  • Denser

  • Rockier

  • Smaller

Outer:

  • Gassy

  • More Moons

  • Bigger

Weight: The pull of gravity on an object

Mass: The amount of matter in an object

Volume: How much space an object takes up

Density: How tightly packed the particles in an object are

Density of Water:

Cold and Salty water is the densest water, which is why we have Deep Ocean currents

Warm and fresh water is the least dense and there floats above all other types of water

*Denser objects sink and less dense objects float*

Newton’s Law of Gravitation:

  • The farther away the object is, the less gravitational pull and the more mass it has the more gravitational pull it has. Distance has more effect than mass.

Planets:

  • Closest to Farthest from Sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune

    • Mercury: Biggest temperature swings between day and night because it has a very thin atmosphere

    • Venus: hottest planet and has acid rain

    • Earth: only planet known to support life and have fresh water

    • Mars: Red from iron and oxygen forming rust on its surface

    • Jupiter: Largest planet, has huge storms, wind patters somewhat similar to those of Earth

    • Saturn: Only planet with visible rings

    • Uranus: Tilts sideways on its axis

    • Neptune: Coldest planet, farthest from sun

Kepler’s Laws

  • Law of Ellipses: All objects that orbit the Sun follow elliptical paths

    • Formula for Eccentricity: Eccentricity = F (the distance between the foci) Ă· A (Length of line that passes through both foci and goes from one end of the ellipse to the other)

  • Law of Equal Areas: A line drawn from the Sun to a planet sweeps equal areas in equal time. A planets orbital velocity (speed at which the planet travels around the sun) changes as its position in its orbit changes

  • Law of Periods: Relates a planets period of revolution (time it takes to go around the Sun once) to its average distance from the Sun

    • Formula: T² = RÂł, where T is the planet’s period of revolution in Earth years and R is the planets mean/average distance from the sun in astronomical units (1 AU = Earths average distance to the sun, which is 150 million km)

Seasons:

  • Caused by Earth’s tilt as well as direct and indirect rays

  • Equinox: When Direct Rays hit the equator

    • 12 hour day and night everywhere

    • Mar and Sep 21st or 22nd

  • Solstice: When Direct Rays hit one of the Tropics

    • Summer Solstice (Jun 21st or 22nd): Direct Rays hit Tropic of Cancer (23.5N) and North Pole has 24 hours of daylight, South Pole has 0 hours of daylight. Northern Hemisphere is in Summer, Southern is in Winter

    • Winter Solstice (Dec 21st or 22nd): Direct Rays hit Tropic of Capricorn (23.5S) and South Pole has 24 hours of daylight, North Pole has 0 hours of daylight. Southern Hemisphere is in Summer, Northern in Winter

  • Perihelion (Jan 4): When Earth is closest to the sun

  • Aphelion (Jun 4): When Earth is farthest from the sun

  • Rotation: Rotating on an axis, the time it takes to complete one rotation is 1 day

  • Revolution: Earth (or any object) orbiting the Sun (or any other object), time it takes to complete 1 revolution is a year

Cause of Direct and Indirect Rays:

  • Due to Earth’s shape, direct rays hit the area between the Tropics at a 90 degree angle, but the farther you get away from them, the more indirect rays you get, and the poles have the most indirect rays.

  • Places that receive indirect rays are generally cooler

Heat Transfer:

  • Conduction: When heat is transferred through solids by direct contact. Ex. Walking on sand.

  • Radiation: Transfer of heat through empty spaces in the form of waves. Ex. The Sun’s heat.

  • Convection: Density driven, particles move as a current, in liquids and gases due to uneven heating.

Heating and Cooling of Land vs. Water:

  • Water needs a lot more heat to warm up and cool down, which is why coastal areas have milder climates than landlocked areas

    • Water needs more heat to warm up and more time to cool down because it has a low specific heat

Milankovitch Cycles:

  • Eccentricity: How Elliptical the Earth’s orbit is. Changes every 100,000 years

  • Axial Tilt: The tilt of the Earth’s axis changes between 21.5 and 24.5 degrees every 41,000 years

  • Precession: Earth’s “wobble” on its axis as it orbits around the sun, changes every 26,000 years

For Milder Climate:

  • Less Eccentricity: Less difference between Perihelion and Aphelion means more milder seasons

  • Less Axial Tilt: So each Hemisphere does not get much more radiation in the summer than it does in the winter

  • Less Precession: Less Direct Rays in Summer means milder summers and More Direct Rays in winter means warmer winters

Convection Currents:

  • Uneven heating

    • Direct vs. Indirect Rays

    • Absorbers & Reflectors

  • Wind is a portion of the convection current

  • Low Pressure —> Low density

  • High Pressure —> High density

  • Land and Sea Breezes

    • Uneven heating

    • Specific Heat of land vs. water

  • Mountain and Valley Breezes

    • Differences in Elevation

Thunderstorms:

  1. Air rises to form a cloud

  2. Downdraft forms from precipitation

  3. Downdrafts take over and storm dies

Lightning:

  1. + charged particles build at top of cloud at base, where - charged particles

  2. Changes in ground get repelled and + are attracted

  3. A step leader made of - charged particles heads towards the ground to meet with a + streamer. When the 2 meet, you get lightning

Thunder:

  • Caused by warm air rapidly expanding and cold air rushing in to replace

Low vs. High Pressure Centers:

Low: Air rises, wind rushes inwards towards L and turns counter clockwise. Cyclones, clouds and storms near fronts

High: Air sinks, wind rushes outwards and clockwise in Northern Hemisphere. Anticyclones, clear skies and dry, at the center of an air mass.

Hurricanes:

  • Late summer to early fall, when ocean is warmest

  • Fuel = warm, moist, rising, air

  • Stages of Development

    • Tropical Depression (Series of thunderstorms)

    • Tropical Storm (35+ mph)

    • Hurricane (75+ mph or 64 knots)

  • Trade Winds push them towards US, then the Westerlies move them along the eastern coast of the US

  • Storm dies if:

    • If it makes landfall —> No moist air to keep it going

    • If it goes over colder areas —> Air can’t rise

  • Eye: calm, eyewall has the worst winds

  • Damage most from storm surge

    • Water expands upwards from low pressure. Winds also help with this.

  • Hurricane Watch: 24-36 hours

  • Hurricane Warning: Within 24 hours

Climate:

  • Reasons that some places are hotter than others:

    • Latitude

    • Elevation

    • Costal vs. Landlocked

    • Direct and Indirect Rays

  • Reasons that some places get more precipitation than others:

    • Costal vs. Landlocked

    • Elevation

    • - Latitude

    • Direct and Indirect Rays

  • Coastal areas have milder climates because water absorbs a lot of sunlight and has a low specific heat and albedo

Atmospheric Terms:

  • Albedo —> The amount of light that a surface can reflect

  • Scattering —> When moving particles or radiation are forced to change paths when heading towards or away from Earth

  • Greenhouse effect —> The process by which heat is trapped in the atmosphere and re emitted by greenhouse gases (Carbon Dioxide, Methane, Water Vapor, etc.)

  • Atmospheric Pressure: The weight on top of you in the atmosphere, decreases with altitude.

Layers of the Atmosphere:

  • Troposphere - Thinnest layer, Gets colder with altitude as pressure decreases and it gets away from the heat of the Earth’s surface; also responsible for weather

  • Stratosphere - Contains the ozone layer, Gets warmer by absorbing UV rays

  • Mesosphere - Coldest layer, temperature and pressure decrease as the layer gets away from the warmth of the ozone layer, also where meteors burn up

  • Thermosphere - Warmest layer, Nitrogen and Oxygen in it absorb short wave radiation, also where auroras form

Moisture Vocabulary:

  • Dew point: The temperature at which the air is saturated. Needed for clouds to form

  • Relative humidity: The amount of water vapor currently in the air compared to the amount that can be in the air; expressed as a percent

  • Specific humidity: The maximum amount of water vapor that can be in a certain amount of air at one time

  • Saturated air: Air that is at the dew point and its relative humidity is 100%

  • Psychrometer: Instrument used to measure the humidity of air

  • Latent Heat: The heat used by a substance to change between states of matter

    • Temp stays the same during a phase change because the heat is being used to change phases

  • Evaporation: The process by which liquid water is turned into a gas (water vapor)

  • Condensation: The process by which water vapor becomes liquid water

  • Sublimation: The process by which a substance goes straight from a solid to a gas

  • Adiabatic cooling: Cooling caused by a change in air pressure

Requirements for Clouds to Form:

  • Rising, moist, warm air

  • Condensation nuclei

  • Low Pressure (so air rises)

  • Expanding air

  • Adiabatic Cooling

Relative Humidity Formula:

(Relative Humidity Ă· Specific Humidity) * 100 = Relative Humidity (%)

Air Masses:

  • Maritime Polar —> cold, wet, cloudy

  • Maritime Tropical —> warm, wet, cloudy

  • Continental Polar —> cold, dry, clear

  • Continental Tropical —> warm, dry, clear

Types of Fronts:

  • Warm Fronts

    • Slow moving

    • Brings cirrus clouds followed by stratus-type clouds

    • Brings steady precipitation followed by warmer temps

  • Cold Fronts

    • Faster

    • Bring cumulus-type clouds

    • Brings heavy precipitation followed by colder temps

  • Stationary Fronts

    • When a warm and cold front collide

    • Similar weather to warm fronts

  • Occluded Fronts

    • Cold front overtakes a warm front until the warm front is not in contact with the ground

    • Similar weather to cold fronts

Deep Ocean Currents:

  • Caused by differences in density from salinity and temperature differences

  • North Atlantic Deep Water, Antarctic Bottom Water

  • Start at the poles and eventually the North Atlantic Deep Water and Antarctic Bottom Water upwells and allows surface currents to travel from the equator northward bringing warm water along our coast (The Gulf Stream)

  • These start the Great Ocean Conveyor a giant convection current in the ocean that transfers heat, oxygen, and nutrients

Surface Currents (Gyres):

  • Affected by winds and Coriolis effect and location of continents

  • Spin Clockwise in Northern Hemisphere, Counter clockwise in Southern Hemisphere

  • Named for what they border

  • Currents from the Equator are Warm, currents from the poles are cold

  • Ex. California (cold), Brazil (warm), Canary (warm), etc.

CO2 and Temperature:

  • As CO2 levels increase, climates get warmer because CO2 is a greenhouse gas, so its a positive feedback loop that helps accelerate the greenhouse effect, allowing for more energy to be re emitted back towards Earth

Climate Change over the past 800,000 years:

  • CO2 levels have increased during interglacial periods and decreased during glacial periods

    Climate Change Indicators:

    • Rising sea levels

    • More ocean acidification

    • Increased CO2 levels

    • Increased methane levels