Earth Science Lecture Notes Review

Flashcards for key vocabulary and concepts from the lecture notes.

Troposphere

The layer of the atmosphere where we live and where weather happens.

Stratosphere

The layer of the atmosphere that contains the ozone layer, which protects us from UV radiation.

Mesosphere

The layer of the atmosphere where meteors burn up.

Thermosphere

The layer of the atmosphere that is super hot and where space shuttles orbit.

Exosphere

The outermost layer of the atmosphere that is very thin and blends into space.

Latent Heat

Heat is absorbed or released when water changes between ice, liquid, and steam.

Convection Cells

Loops of moving air formed by changes in temperature, density, and pressure.

Adiabatic Processes

A change in temperature without adding or losing heat. For example, air cools as it rises and expands, and warms as it sinks and compresses.

Hadley Cells

Have lots of rising warm air, resulting in rainforests.

Ferrell Cells

Have more variable weather and are located between the tropics and poles.

Polar Cells

Have cold air that sinks and are located near the poles.

Jet Streams

Narrow bands of fast-moving air high up in the atmosphere, typically found near the top of the troposphere

Coriolis Effect

The effect of the Earth spinning, causing moving air and water to curve instead of going straight (right in the northern hemisphere, left in the southern hemisphere).

High Pressure

Associated with air sinking and usually clear skies.

Low Pressure

Associated with air rising and usually clouds and rain.

Cyclone

Low pressure, air rises, stormy, spins counterclockwise (in the north).

Anticyclone

High pressure, air sinks, clear skies, spins clockwise (in the north).

Thermocline

A layer in the ocean where the temperature drops quickly with depth.

Surface Circulation

Mostly driven by wind, especially the trade winds, pushing water and creating large rotating systems.

Gyres

Big circular currents in oceans formed by winds and the Earth’s rotation (Coriolis effect).

Deep Water Circulation

Driven by density differences (cold + salty = heavy = sinks).

Thunderstorm

Involves rotating, rising air and needs warm, moist air to start.

Cumulus Stage

Warm air rises, clouds build up.

Mature Stage

Heavy rain, lightning, thunder, maybe hail.

Dissipating Stage

Air sinks, storm dies out.

Single-cell

Short, small storm

Multi-cell

Cluster of storms.

Supercell

Strong, long-lasting storm that can cause tornadoes.

Hurricane

A huge rotating storm with strong winds and rain, forming over warm ocean water

Eye

Calm center of a hurricane.

Eyewall

Strongest winds and rain in a hurricane.

Rainbands

Outer spirals with more rain and wind in a hurricane.

Storm Surges

Water pushed onto land by hurricanes.

Saffir-Simpson Scale

A scale that classifies hurricanes (Category 1 to 5).

Linear Scale

Increases evenly (e.g., 1, 2, 3, 4…).

Logarithmic Scale

Increases by powers of 10. Used to show big changes more clearly

Forcing Factor

Something that pushes or changes the climate (like sunlight or volcanoes).

Response

How the climate reacts to a forcing factor (like warming or ice melting).

Tectonic Forcing

Moving continents, volcanoes, mountains.

Orbital (Milankovitch Cycles)

Changes in Earth’s orbit and tilt.

Solar Strength

How much energy the Sun gives off.

Response Time

How quickly the climate reacts after a forcing happens.

Positive Feedback

A change causes more of itself, like melting ice reflects less sun, warms Earth, and melts even more ice.

Negative Feedback

Fights change, like more clouds cool the Earth when it gets too warm.

Albedo

Reflectiveness; Ice and snow reflect sunlight (cooling effect); dark surfaces absorb it (warming effect).

Climate Proxy Record

Indirect evidence of past climate, such as tree rings, ice cores, and sediments

Isotope

An atom with a different number of neutrons

Icehouse

Cold earth, polar ice sheets

Greenhouse

Warm Earth, little or no ice at the poles.

Glacial

Cold periods within Icehouse times (like the Ice Age).

Interglacial

Warmer periods between glacials (like right now!).

Faint Young Sun Paradox

The Sun was weaker billions of years ago, so Earth should’ve been frozen.

Weathering Process

Rain pulls CO₂ from the air, forms a weak acid that breaks down rocks, and locks the CO₂ away in solid rock for millions of years.

Polar Position Hypothesis

Ice ages happen when continents sit near the poles, making it easier for ice to form and stay frozen

Pangaea

A supercontinent (all land together).

BLAG Hypothesis

The BLAG Hypothesis says more seafloor volcanoes = more CO2 = a warmer Earth

Uplift Weathering Hypothesis

Forming mountains helps remove CO2 from the air, slowly cooling the Earth

Ocean Heat Transport Hypothesis

Oceans move heat around the planet; High sea level = better heat movement = warmer Earth; Low sea level = less heat movement = cooler Earth, more glaciers.

Snowball Earth

Theory that Earth was fully frozen (~650 million years ago).

PETM (Paleocene-Eocene Thermal Maximum)

Massive warming caused by greenhouse gases (~56.5 mya).

Younger Dryas

Sudden cooling during a warm period (~13,000 years ago), caused by meltwater from glaciers slowing ocean currents.

Little Ice Age

A period from approximately 1300–1800s that was only 1–1.5°C cooler but had a big impact on farming and freezing rivers.

4x Model

What CO₂ levels go up 4 times from pre-industrial levels.

PHAs

Potentially Hazardous Asteroids. Big and come close to Earth

Asteroid

A rocky object in space, mostly found in the asteroid belt (between Mars & Jupiter).

NEAs

Near-Earth Asteroids

Comet

A dirty snowball – ice + dust found in the Oort Cloud or Kuiper Belt (outer solar system).

Carbonaceous Chondrites

Special stony meteorites with carbon & water, might have helped start life on Earth.

Chondrule

A small, round grain formed when dust melted and cooled in early space.

Kinetic Energy

Energy of motion; Formula: KE = ½ mv²; Bigger and faster = more energy, bigger impact.

Hypervelocity

Super high speeds, typical of space impacts

Ejecta Blanket

Debris thrown out from the crater that forms a layer around the crater with shattered rock and melted pieces.

NEO or NEA

Neo = Near-Earth Object; NEA = Near-Earth Asteroid → These are objects that come close to Earth.

Torino Scale

A scale for risk of space impacts (0 = no danger, 10 = extinction).

Apophis

Comes close in 2029 and 2036 (currently not expected to hit).

Breccias

Rock fragments stuck together by impact.

Airburst

As a meteoroid enters Earth’s atmosphere, it hits air resistance at high speed

Mass Extinction

A large number of species die off, is widespread, happens quickly, and affects many types of life.

Flood Basalts

Massive volcanic eruptions over thousands of years that release lava, CO2, and sulphur gases.

Methane Clathrates

Methane gas is trapped in frozen ocean sediments. It increases greenhouse gases and causes rapid global warming.

Anoxic Ocean Water

No oxygen in parts of the ocean, causing marine life to suffocate.

One-Cause Theory

One repeated event caused all extinctions (e.g., asteroid every 26 million years).

Individual-Cause Theory

Each mass extinction had its own unique trigger.

26 Million Year Theory

Mass extinctions and other major Earth events happen in regular cycles, roughly every 26 million years

33-Million-Year Theory

Links flood basalts, impacts, magnetic field reversals, and mass extinctions.

Precambrian Eon

The earliest and longest part of Earth’s history, covering about 88% of Earth’s timeline!

Earliest Life Forms

Single-celled organisms like bacteria, archaea and cyanobacteria

Source of Oxygen

From cyanobacteria doing photosynthesis.

Phanerozoic Eon

Covers the last 540+ million years; Most of Earth’s complex life and extinction events happened during this time; Includes the Big 5 mass extinctions.

Cambrian Period Extinction Causes (Likely)

Glacial cooling, sea level drop, anoxic oceans

Ordovician Period Extinction Cause

Rapid ice age, sea level drop

Devonian Period Extinction Causes

Asteroid impact, Anoxic oceans

Triassic Period Extinction Cause

Volcanoes added CO2, warming oceans, which released methane and removed oxygen from the water

Zircon

A mineral used for age dating because it’s super durable and contains uranium, which helps accurately date rocks.

Bedout Crater

Off the coast of Australia — possible impact site.

Wilkes Land Crater

Under Antarctica and is possibly linked to this extinction.

Gradualists

Believe dinosaurs were already declining slowly before the asteroid.

Catastrophists

Believe a sudden event (like an asteroid) caused rapid extinction.

Ejecta Layer

Debris and melted rock blasted out by the impact.

Fireball Layer

Soot and ash from fires and atmosphere heating.